MD Hubert Blain
email: h-blain@chu-montpellier.fr

MD Fiona Dabas

MD Samia Mekhinini

Marie-Christine Picot

MD Stéphanie Miot

MD Jean Bousquet

MD Chokri Boubakri

MD, PhD Audrey Jaussent

PhD Pierre Louis Bernard

MD Marie- Christine Picot

Hubert Blain

Effectiveness of a programme delivered in a falls clinic in preventing serious injuries in high-risk older adults: A pre-and post-intervention study

Keywords: NCT03737487 falls prevention clinic, falls, injurious falls, comprehensive geriatric assessment, ageing

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Falls are one of the main causes of decreased functioning, admission to emergency department, hospital and nursing homes, and death in older subjects [START_REF] Oliver | Falls in older people-can we really make a difference[END_REF]. Falls prevention is therefore a priority in promoting active and healthy ageing and reducing healthcare resource utilization in older subjects [START_REF]European Innovation Partnership on Active and Healthy Ageing[END_REF][START_REF]Stopping Elderly Accidents, Death, and Injuries (STEADI[END_REF][START_REF] Blain | EUGMS Falls and Fracture Interest Group; European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO), Osteoporosis Research and Information Group (GRIO), and International osteoporosis Foundation (IOF). A Comprehensive Fracture Prevention Strategy in Older Adults: The European Union Geriatric Medicine Society (EUGMS) Statement[END_REF]. Randomized-controlled trials indicate that multiple component interventions, including exercise and another component such as education or home-hazard assessment, do not seem to be effective in preventing injurious falls in community-dwelling older persons at high risk of falling and in nursing home residents [START_REF] Cameron | Interventions for preventing falls in older people in care facilities and hospitals[END_REF][START_REF] Hopewell | Multifactorial and multiple component interventions for preventing falls in older people living in the community[END_REF]. For older people at high risk of falling, especially those with recurrent falls, or in fallers with significant gait, balance or muscle strength disorders, current guidelines recommend an individualized assessment of risk factors of falls and a tailored multifactorial intervention programme. This includes exercise, gradual withdrawal of fall-risk-increasing-drugs (FRIDs), optimization of vision and health conditions, home safety interventions, multifaceted podiatry, and calcium and vitamin D supplementation if needed [START_REF]Stopping Elderly Accidents, Death, and Injuries (STEADI[END_REF][START_REF]Summary of the Updated American Geriatrics Society/British Geriatrics Society clinical practice guideline for prevention of falls in older persons[END_REF].

The efficacy of such a strategy for reducing injurious falls is however not fully demonstrated in randomized-controlled trials [START_REF] Hopewell | Multifactorial and multiple component interventions for preventing falls in older people living in the community[END_REF].

Falls clinics are one approach by which older people at risk of falls and injuries can be managed in real clinical practice, addressing all identified modifiable risk factors.

While falls clinics have been reported in the literature since 1988, only one randomized-controlled trial has observed a significant reduction in fall-related injuries (-26%) in patients among whom 45% had a history of fall in the previous year [START_REF] Palvanen | Effectiveness of the chaos Falls Clinic in preventing falls and injuries of home-dwelling older adults: a randomised controlled trial[END_REF].

Before-after studies have been conducted to overcome ethical difficulties in conducting randomized-controlled trials in patients at high risk of injurious falls. Most of those pre-post design studies have observed an efficacy of falls clinics in improving balance, mobility, fear of falling [START_REF] Perell | Outcomes of a consult fall prevention screening clinic[END_REF][START_REF] Sze | The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program[END_REF][START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF][START_REF] Baker | Intervention to Prevent Falls: Community-Based Clinics[END_REF], fall rates [START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF][START_REF] Baker | Intervention to Prevent Falls: Community-Based Clinics[END_REF], and use of fall-related health services [START_REF] Perell | Outcomes of a consult fall prevention screening clinic[END_REF][START_REF] Baker | Intervention to Prevent Falls: Community-Based Clinics[END_REF]. Only one pre-post study, conducted in 13 Australian falls clinics and 254 elders, has observed a 55% significant reduction of injurious falls 6 months after clinic attendance [START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF]. In those two previous studies with positive outcomes on injurious falls [START_REF] Palvanen | Effectiveness of the chaos Falls Clinic in preventing falls and injuries of home-dwelling older adults: a randomised controlled trial[END_REF][START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF], most fall-related injuries were bruising or other moderate injuries. Efficacy on serious fall-related injuries did not obtain significance, possibly due, for ethical reasons, to the insufficient representation of patients with high risk of injurious falls in the randomized-controlled trial [START_REF] Moore | Translating a multifactorial fall prevention intervention into practice: a controlled evaluation of a fall prevention clinic[END_REF] and to the low adherence for interventions, such as exercise programmes [START_REF] Sze | The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program[END_REF], and home and medication modification, in the pre-post intervention study [START_REF] Clemson | The effectiveness of a community based program for reducing the incidence of falls in the elderly: A randomized trial[END_REF].

In the present 6-month pre-post intervention study, we included older patients consecutively referred to a specialist falls prevention clinic after repeated falls in the previous year, or after a fall in the past 12 months associated with significant balance, gait, or strength disorders. The main objective was to determine, in those high risk patients, the effect on serious falls-related injuries of a tailored multifactorial programme delivered after a 3-hour assessment by a physiotherapist, an occupational therapist, a podiatrist, and a geriatrician. Secondary aims were to evaluate over the 6-month follow-up period the effect of the intervention programme on moderate injuries, falls rate, falls risk, fear of falling, mobility, ability to perform activities of daily living (ADL), patient's adherence to recommendations and patient's or caregiver's satisfaction with the programme.

Method

Setting and participants

The Montpellier falls prevention clinic (FPC) is a referral-based clinic specialized in the prevention of falls and fractures among patients aged 65+ (http://www.chumontpellier.fr/fr/crepc/). The FPC is a member of the European Commission in its European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) A2 action plan [START_REF] Blain | Living Lab Falls-MACVIA-LR: The falls prevention initiative of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) in Languedoc-Roussillon[END_REF]. The main mission of the clinic is to identify the underlying causes of the patients' falls, and to address all modifiable risk factors in collaboration with family physicians.

We analysed data from a cohort of patients aged 65 and over, consecutively referred to the FPC over a 11-month period after recurrent falls in the previous year, or after a fall in the past 12 months associated with gait, balance, or strength disturbance at baseline. A gait disturbance was defined by an inability of the patient to perform the Timed Up and Go test in less than 14 seconds [START_REF] Podsiadlo | The timed ''Up & Go'': A test of basic functional mobility for frail elderly persons[END_REF]. A balance disturbance was defined by an inability of the patient to stand on one leg for at least 5 seconds [START_REF] Vellas | One-leg balance is an important predictor of injurious falls in older persons[END_REF]. A low muscle strength was defined by a grip strength of 37 kg or less for men and 21 kg or less for women [START_REF] Pijnappels | Identification of elderly fallers by muscle strength measures[END_REF]. As this is a cohort study, a STROBE checklist has been included in the supplementary materials.

A fall was defined as an

Multidisciplinary fall risk and geriatric comprehensive assessment

All patients underwent the same multidisciplinary fall risk and geriatric comprehensive assessment by health care professionals of the clinic. The assessment was performed on a routine basis and included the following steps:

-Calculation of BMI based on height and weight, measured by a nurse to the nearest 0.5 cm and 0.1 kg, respectively (kg/m²).

-A 40-min assessment of balance, walking speed, muscle strength, activity, and functional status by a physiotherapist using: (1) the Short Physical Performance Battery (SPPB), 20 the Timed-Up-and-Go Test (TUG) [START_REF] Podsiadlo | The timed ''Up & Go'': A test of basic functional mobility for frail elderly persons[END_REF], the Tinetti test [START_REF] Tinetti | Fall-risk evaluation and management: Challenges in adopting geriatric care practices[END_REF], and both hands grip strength measurements with a Jamar hand dynamometer [START_REF] Pijnappels | Identification of elderly fallers by muscle strength measures[END_REF], [START_REF]European Innovation Partnership on Active and Healthy Ageing[END_REF] questionnaires to quantify the need for technical help for inside and outside walking (human aid, walking stick, walker, wheelchair), and (3) the activities of daily living (ADL) completed with the caregiver if necessary [START_REF] Jette | Toward a common language of disablement[END_REF].

-A 40-min assessment by an occupational therapist, including a detailed questionnaire on social support, living situation and home environment, completed with the caregiver if necessary. Patients were categorized as not concerned, a little concerned, quite concerned, or very concerned by the risk of falling [START_REF] Vellas | Fear of falling and restriction of mobility in elderly fallers[END_REF]. Cognitive function was assessed using the mini mental state examination (MMSE) that was considered normal when the score was 25 or higher. Cognitive disorder was categorized as severe when the MMSE score was less than 10, moderate between 10 and 19 and mild between 20 and 24.

-A 20-min assessment by a podiatrist including an examination of the patient's feet and footwear.

-A 60-min assessment by a geriatrician including a description of previous falls in the previous year (number, injuries, circumstances), a review of current medications and medical history, and an in-depth examination of the patient to detect possible contributors or risk factors for falling (especially FRIDs, joint, ENT, psychiatric, neurological, pulmonary, gut or metabolic disorders, postural hypotension, and signs of osteoporosis, artery and heart diseases, including cardiac failure and carotid sinus hypersensitivity, signs of sleep apnoea, of urinary infections, retention or incontinence) [START_REF]Summary of the Updated American Geriatrics Society/British Geriatrics Society clinical practice guideline for prevention of falls in older persons[END_REF].

-A blood collection with complete blood count (with serum electrolytes (natremia, glycaemia, kaliemia, calcemia), urea nitrogen and serum creatinine, C-reactive protein, transaminases and gamma-glutamyl transferase, thyroid-stimulating hormone, 25OH vitamin D, electrocardiogram), or other investigations (dual-energy X-ray absorptiometry, for example) or specialist referral were performed upon request from the geriatrician. Patients without an eye examination in the past year were referred systematically to an ophthalmologist.

-A 20-min review meeting with the 4 healthcare professionals in order to prioritize recommendations to be provided.

The conclusion of the assessment was then summarized by the geriatrician for the patient or the caregiver and appropriate recommendations and prescription were provided. In patients with a TUG test ≥ 14 seconds, prescriptions systematically included physiotherapy sessions (2 sessions per week for 6 months, including balance, gait, flexibility, and strengthening exercises adapted to baseline assessment, procedures to get up after a fall, and foot and ankle exercises). Patients with a TUG test < 14 seconds were referred to "MACVIA-France Equilibre Prévention de la Chute Autonomie Santé", in order to register for community physical activity programmes organised for older adults at high risk of falling (one-hour exercise sessions twice a week for 6 months by trained staff) [START_REF] Blain | Living Lab Falls-MACVIA-LR: The falls prevention initiative of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) in Languedoc-Roussillon[END_REF]. In patients with transport difficulties, physiotherapy at home was prescribed whatever the TUG result.

Patients were systematically given 80 000 UI oral vitamin D supplements and GPs were advised to adapt the treatment according to baseline blood vitamin D level or in compliance with national guidelines.

According to the patient's profile, other prescriptions included podiatry (lesion debridement, footwear advice, foot orthoses, for example), environment changes, adapted technical support, modification of drug use to optimize underlying conditions, to progressively withdraw FRIDs, and to treat osteoporosis. The likely diagnoses and recommendations were noted in the medical report that was handed over to the patient or the caregiver for the patient's GP, along with the prescriptions, and sent also by mail to the GP. Recommendations remained under the GP's control with the possibility of another consultation if needed. Patients or their legal representatives gave their consent to be interviewed by phone 6 months after the visit in order to provide information on the occurrence of new falls and falls-related injuries since the visit, on recommendations actually set up, on the patient's current functional status, and to express their view on the programme. A copy of the questionnaires used and an example of the routine assessment performed in the falls clinic are included in the supplementary materials.

Data analysis

The qualitative variables were described with frequency and proportions for each category. The distributions of the quantitative variables were tested by the Shapiro-Wilk test and the description of these variables was specified using the mean with the

Results

Characteristics of the patients

Among the 212 patients admitted to the clinic in 11 consecutive months, 160 had a history of recurrent falls in the previous year or of a fall associated with a balance, gait, or muscle strength problem. Twenty-three patients were lost to follow-up and 3 had incomplete data for at least one outcome. The 26 patients not included in the final analysis did not differ in age, gender, ADL, and living status from the patients entered in the analysis.

Baseline characteristics of the 134 analyzed patients are displayed in Table 1 and primary and secondary outcomes are displayed in Table 2.

Discussion

In this 6-month pre-post intervention study conducted in older patients referred to a specialist falls prevention clinic after recurrent falls, or after a fall with significant gait, balance, or strength impairments, we observed that a tailored multifactorial programme may reduce the number of serious and moderate fall-related injuries, the number of falls and fallers, the fear of falling, and may maintain or improve mobility and ability to perform ADLs.

Our study has several strengths. As far as we know, this study is the first before-after study to show the efficacy of a falls clinic in preventing serious injuries in high risk older patients defined using current guidelines (fallers with recent history of recurrent falls or with gait, balance, or muscle strength disorder) [START_REF]Stopping Elderly Accidents, Death, and Injuries (STEADI[END_REF][START_REF]Summary of the Updated American Geriatrics Society/British Geriatrics Society clinical practice guideline for prevention of falls in older persons[END_REF]. The methodology used herein has been identical for all consecutive older patients and our patients have demonstrated a high level of adherence to the programme. The present study does however have several limitations. This study is observational and without randomization. However, randomized-controlled studies generally exclude frail patients at the highest risk of falls and injuries and apply strict eligibility criteria that reduce the generalizability of their results in daily practice. On the other hand, pre-post studies conducted in patients recruited consecutively have the advantage of evaluating a real-world practice, operating within the context of usual care, and involving elders whatever their health and psychological status, and socioenvironmental characteristics. Present results reflect the real situation of a falls prevention clinic, and provide estimates of the result that can realistically be expected by the patient, the caregiver, and the GP referring patients at high risk of fall and injury to this kind of setting.

Even if the information was recorded by using the same questionnaires at baseline and at 6 months after the visit, interviewer bias is a possible limitation

of the present study. Indeed, pre-intervention data were collected by health care professionals from the clinic and post-intervention data were collected by independent researchers. The fact that independent researchers were not aware of the results of the baseline assessment and were not involved in the clinic has contributed to minimizing the interviewer bias on outcomes of interest including satisfaction with the programme.

Reporting bias is a limitation of cohort studies that compare subjects' fall rates before and after intervention [START_REF] Perell | Outcomes of a consult fall prevention screening clinic[END_REF][START_REF] Sze | The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program[END_REF][START_REF] Baker | Intervention to Prevent Falls: Community-Based Clinics[END_REF]. However, such bias is unlikely to fully explain the reduction in the fall-related injuries, which are less susceptible to reporting bias [START_REF] Ganz | Monitoring falls in cohort studies of community-dwelling older people: effect of the recall interval[END_REF].

Besides, some studies have shown that falls recall has an acceptable sensitivity and specificity, especially when patients without moderate or severe cognitive impairment (who represent 75% of our patients) or their caregivers are interviewed [START_REF] Ganz | Monitoring falls in cohort studies of community-dwelling older people: effect of the recall interval[END_REF][START_REF] Sanders | Monitoring falls in cohort studies of community-dwelling older women[END_REF].

In the present study, recommendations of the occupational therapists were based on a questionnaire and not followed by a home visit. This limitation may explain why only 58% of the recommendations given by the occupational therapist had been completed. This limitation may have reduced the impact of our programme on preventing falls and mobility impairments [START_REF] Sze | The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program[END_REF].

There may also be some limitations of telephone surveys compared to face-to-face interviews. The telephone survey has however the advantage of improving the feasibility of data collection. Moreover, the telephone survey seems to provide similar results compared with face-to-face questioning for collecting data on the risks and circumstances of falls [START_REF] Mackintosh | Telephone and face-to-face interviews generate similar falls circumstances information from community-dwelling adults with stroke[END_REF].

Our population is different from those in other studies where participants had a lower risk of serious falls-related injuries. In the present study, 30.5% had serious fallsrelated injuries in the previous 6 months vs around 10% in previous studies [START_REF] Sze | The efficacy of a multidisciplinary falls prevention clinic with an extended step-down community program[END_REF][START_REF] Moore | Translating a multifactorial fall prevention intervention into practice: a controlled evaluation of a fall prevention clinic[END_REF][START_REF] Tinetti | Fall-risk evaluation and management: Challenges in adopting geriatric care practices[END_REF]. The effect of the intervention was larger than anticipated with a respective 80% and 42% reduction of serious and moderate fall-related injuries and a 66% reduction of the risk of falling. We believe this risk reduction to be clinically important, especially since the mobility of patients was maintained over the 6-month follow-up.

We observed a high percentage of adherence (85.7%) to the top three proposed interventions (physiotherapy, medical review and referrals, and podiatry). In comparison with the 2 studies that have shown efficacy of the falls clinic approach in preventing injurious falls, adherence was similar to that observed in the randomizedcontrolled trial [START_REF] Palvanen | Effectiveness of the chaos Falls Clinic in preventing falls and injuries of home-dwelling older adults: a randomised controlled trial[END_REF] but much higher than that measured in the pre-post clinic study (14.3%) [START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF]. In this latter study, the more severe patients, i.e. participants with poor balance and mobility performance, were at the highest risk of loss to follow-up [START_REF] Hill | Effectiveness of falls clinics: an evaluation of outcomes and client adherence to recommended interventions[END_REF].

The high percentage of adherence to the programme that might reflect the high level of satisfaction of patients and caregivers for the information delivered during the visit [START_REF] Clemson | The effectiveness of a community based program for reducing the incidence of falls in the elderly: A randomized trial[END_REF][START_REF] Mcinnes | Evidence review on older people's views and experiences of falls prevention strategies[END_REF][START_REF] Hill | What factors influence community-dwelling older people's intent to undertake multifactorial fall prevention programs?[END_REF] and low drop-out percentage in our patients at high risk of injuries may have helped to optimize the effectiveness of the programme on serious falls. The fact that we prioritized a limited number of interventions may also have contributed to the good adherence to recommended interventions [START_REF] Baker | Intervention to Prevent Falls: Community-Based Clinics[END_REF][START_REF] Hill | Don't lose sight of the importance of the individual in effective falls prevention interventions[END_REF].

Patients included in the present study were offered a wide range of assessment and management options provided by a multidisciplinary multifactorial risk assessment.

Results of the present study cannot be extrapolated to non-fallers and to a morelimited range of assessment and management options. Because fall risk reduction obtained through an assessment in a fall clinic may lessen over time [START_REF] Wagner | Preventing disability and falls in older adults: A population-based randomized trial[END_REF], it remains to be determined whether the effects on injurious falls of the multifactorial fall risk assessment described herein persist beyond the 6 months following the intervention.

Finally, a study of the economic consequences of the present clinical findings is also required and a multicentre study would help to establish generalizability of our results. Based on the present results, a larger study could have the power to determine the effect of the intervention on the most costly outcomes that are fractures and admissions to hospital.

Conclusions

Fallers with recurrent falls or with balance, gait, or muscle strength problems are at a particularly high risk of new falls and injuries. These patients are unlikely to receive multifactorial falls prevention interventions in regular clinical practice. The present 6month before-after study suggests that the referral of such patients to a specialist falls prevention clinic may be associated with a reduction of the number of falls and falls-related injuries, and of the fear of falling, and may be associated with an improvement of functional status and a maintenance of mobility. The overall favourable perception of patients and caregivers for the multidisciplinary assessment, the information given about falls risk, and the recommendations provided may have helped to maximize the adherence to the programme.

Contributors

Hubert Blain contributed to study conceptualization, the investigation, project administration, study resourcing, supervision, validation, and drafting the original manuscript.

Fiona Dabas contributed to study conceptualization, data curation, the investigation, study resourcing, and drafting the original manuscript.

Samia Mekhinini contributed to study conceptualization, data curation, the investigation, and study resourcing.

  "unexpected event in which the participant comes to rest on the ground, floor, or other lower level" [7]. Injurious falls included falls complicated by serious or moderate injuries. Falls with serious injuries were those that caused fractures, head injuries requiring admission to hospital, joint dislocations, sprains accompanied by reduced physical function, other nonspecified serious joint injuries, and lacerations requiring sutures. Falls with moderate injuries were those that resulted in bruising, sprains, cuts, abrasions, or reduction in physical function for at least three days or in medical help [16].

  standard deviation and/or the median, minimum and maximum values. The comparisons pre-versus post-intervention were made using the paired Student's test if the distributions were Gaussian. Otherwise, the Wilcoxon test for paired series was used. The evolution of the qualitative variables before and after intervention was tested with the Mc Nemar Chi² test or the Bowker symmetry test if the response modalities were greater than 2. The significance threshold was set at 5% for all tests used. The statistical analysis was performed at the epidemiology and clinical research unit of Montpellier University Hospital with SAS software version 9 (SAS Institute, Cary, N.C.).

  Marie-Christine Picot contributed to study conceptualization, data analysis, methodology, and software/ Stéphanie Miot contributed to study conceptualization and supervision.Jean Bousquet contributed to study conceptualization, methodology, supervision, and drafting the original manuscript.Chokri Boubakri contributed to study conceptualization.Audrey Jaussent contributed to study conceptualization, data analysis, methodology, and software.Pierre Louis Bernard contributed to study conceptualization, supervision, and drafting the original manuscript.

*FigureFigure 2 │Satisfaction with the programme reported 6

 26 Figure 1│Main factors identified during the fall-risk assessment

Table 1│Patients ' characteristics at baseline

 1│Patients

	Sex [No (%)]	No=134
	-Male	41 (30.6)
	-Female	93 (69.4)
	Age	No =134
	[mean, (SD)]	81.6 (7.2)
	[median, (min;max)]	83.0 (63.0;98.0)
	Body Mass Index	No=104
	[mean, (SD)]	25.7 (4.8)
	[median, (min;max)]	24.7 (16.7;41.7)
	Living status [No (%)]	No =134
	-Home	116 (86.6)
	-Institution	18 (13.4)
	Referred by [No (%)]	No =128
	-GP	69 (53.9)
	-Other specialists	22 (17.2)
	-Emergency ward	12 (9.4)
	-Other hospital ward	12 (9.4)
	-Mobile geriatric unit	3 (2.3)
	-Self-referred	4 (3.1)
	-Other	6 (4.7)
	Charlson Comorbidity Index	No=134
	[mean, (SD)]	5.1 (1.5)
	[median, (min;max)]	5 (2;9)
	Cognitive disorders	No=127
	-None [No (%)]	75 (59.1)
	-Mild [No (%)]	17 (13.4)
	-Moderate [No (%)]	20 (15.7)
	-Severe [No (%)]	15 (11.8)
	One leg stand test	No=107
	-< 5 seconds [No (%)]	84 (78.5)

Table 2│Patients ' outcomes at baseline and 6 months after fall clinic attendance

 2│Patients

	Patients with Falls in the past 6	No=131	No=131	p<0.0001
	months
		6 (4.6)	89 (67.9)
	-No fall [No (%)]
		Baseline	6 months	P value*
	-Fall with no injury [No (%)]	66 (50.4)	after clinic 23 (17. 6)
	-Moderate injury [No (%)]	19 (14.5)	attendance 11 (8.4)
	ADL [mean, (SD)] -Serious injuries [No (%)]	No=122 5.1 (1.3) 40 (30.5)	No =122 4.8 (1.6) 8 (6.1)	<0.001
	[median, (min;max)]	5.5 (0.0;6.0)	5.5 (0.0;6.0)
	-]0-2] [n (%)]	7 (5.7)	12 (9.9)	0.0430
	-]2-4] [n (%)]	17 (13.9)	17 (13.9)
	-]4-5] (%)]	18 (14.8)	22 (18.0)
	->5 [n (%)]	80 (65.6)	71 (58.2)
	Outdoor displacements [No (%)]	No=133	No=133	p=0.20
	-Do not walk	7 (5.3)	15 (11.3)
	-With a wheelchair	4 (3.0)	5 (3.8)
	-Walk with a walker	14 (10.5)	13 (9.8)
	-Walk with a stick	45 (33.8)	47 (35.3)
	-Walk with a human help	4 (3.0)	8 (6.0)
	-Independent walking	59 (44.4)	45 (33.8)
	Indoor displacements [No (%)]	No=132	No=132	p=0.21
	-Do not walk	0 (0.0)	6 (4.5)
	-With a wheelchair	2 (1.5)	2 (1.5)
	-Walk with a walker	14 (10.6)	18 (13.6)
	-Walk with a stick	34 (25.8)	20 (15.2)
	-Walk with a human help	1 (0.8)	3 (2.3)
	-Independent walking	81 (61.4)	83 (62.9)
	Fear of falling	No=95	No=95	0.0015
	-Not concerned [No (%)]	31 (32.6)	44 (46.3)
	-A little concerned [No (%)]	17 (17.9)	27 (28.4)
	-Quite concerned [No (%)]	20 (21.1)	11 (11.6)
	-Very concerned [No (%)]	27 (28.4)	13 (13.7)

Table 3 │ Description of the consequences associated with moderate and serious falls*

 3

	Consequences	6 months before	6 months after
			clinic attendance	clinic attendance
		Hematoma or	13	10
		wound
		Head trauma	4	0
		Falls with medical	1	1
	Moderate injuries	care Falls with disability	1	0
		> 48 h
		Total	19	11
		Hip fracture	4	3
		Pelvis fracture	3	0
		Spine fracture	6	1
		Humeral fracture	1	0
		Wrist fracture	5	0
		≥ 3 ribs fracture	3	1
		Joint dislocation	0	1
	Serious injuries	Head trauma with hospitalisation

Acknowledgments:

The authors are very grateful to Anna Bedbrook, for pre-and post-submission editorial assistance.

Funding

This study did not receive any specific funding.

Main outcome measures

The primary outcome was the number of serious fall-related injuries in the 6 months post-clinic in comparison with the 6 months pre-clinic. Secondary outcomes included the occurrence of moderate fall-related injuries, of falls, technical help needed for inside and outside walking, fear of falling, ADL score, interventions actually set up among those proposed, and satisfaction with the programme.

Primary and secondary outcomes were collected 6 months after the clinic visit via a phone questionnaire administered to the patients or to their legal representatives by two independent researchers (two medical residents) who had no link with the falls clinic. When participants or their legal representatives had difficulties in specifying the type of injury related to a fall that occurred in the 6 months after the visit, consent was obtained from participants or their legal representatives to interview the GPs or the nurses to obtain further information. The study was approved by the Clinical Research Ethics Committee of the University Hospital of Montpellier (France)(IRB-MTP181016; ClinicalTrials.gov ID: NCT03737487).

Sample size

Considering a rate of 20% of serious falls-related injuries in the 6-month period before clinic attendance, a sample of 102 subjects was found to be required to demonstrate a 50% reduction of serious falls-related injuries in the 6 months postclinic, with an alpha and beta error of 5% and a statistical power of 95%. To allow for study drop-outs, there was an oversampling of 20%, which determined a final minimum sample of 113 subjects.

Serious injuries

The number of patients with at least one serious injury was significantly lower in the 6 months after vs preceding clinic attendance [8 (6.1%) vs 40 (30.5%); p<0.0001)]. The types of injuries are reported in Table 3.

Other outcomes

The rate of patients with moderate fall-related injuries decreased significantly from 45.0% to 14.5% (p<0.0001). The rate of fallers was significantly lower 6 months after vs before clinic attendance (32.1% vs 95.4%, respectively; p<0.0001).

The number of falls per patient was significantly lower 6 months after clinic attendance than 6 months before (-5.2 ± -20.4 falls per patient, respectively; p< 0.001).

Fear of falling was significantly lower at 6 months post-clinic when compared to baseline, and mobility was maintained. Ability to perform ADLs improved significantly (5.6% had ADL score ≤ 2 at baseline vs 9.8% 6 months after clinic attendance; p<0.001). Figure 1 shows risk factors of falling documented during the assessment, with 2.2 risk factors identified per patient on average.

Adherence of patients to interventions was > 70%, except for community exercises and home modifications (Table 4).

Except for the delay to obtain an appointment and the duration of the assessment and examination considered as too long by some patients and caregivers, more than 70% of patients or caregivers were satisfied with the pertinence of the assessment, the information given, and the recommendations provided (Figure 2).

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

Institutional ethics and research board approval was obtained. The study was approved by the Clinical Research Ethics Committee of the University Hospital of Montpellier (France)(IRB-MTP181016; ClinicalTrials.gov ID: NCT03737487).

Provenance and peer review

This article has undergone peer review.

Research data (data sharing and collaboration)

Anonymised patient-level data are available on reasonable request from the corresponding author at h-blain@chu-montpellier.fr.


Marie Sauvadet

Nicolas Fanin

Matthieu Chauvat

Isabelle Bertrand
email: isabelle.bertrand@inra.fr

decomposition improve our understanding of bacterial and fungal successions?

Keywords: Soil, pyrosequencing, decomposition, succession dynamics, microbial community structure

diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

decomposition progresses has been challenged by several studies [START_REF] Rousk | Revisiting the hypothesis that fungal-to-bacterial dominance characterizes turnover of soil organic matter and nutrients[END_REF][START_REF] Purahong | Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition[END_REF]. At the same time, the ecological attributes of both bacterial and fungal decomposers have been increasingly used in studies to better assess changes in carbon-(C) and nutrient-use efficiencies during litter decomposition: early decomposers (often assimilated to copiotrophs) have high nutritional requirements and preferentially consume rich and soluble substrates, whereas late-decomposers (often assimilated to oligotrophs) exhibit low growth rates and consume poor and complex C compounds [START_REF] Fanin | Aboveground litter quality is a better predictor than belowground microbial communities when estimating carbon mineralization along a land-use gradient[END_REF][START_REF] Ho | Revisiting life strategy concepts in environmental microbial ecology[END_REF]. Most substrates used to assess the validity of the copiotroph-oligotroph model are synthetic (e.g., glucose and simple carbohydrates) or relatively labile (e.g., leaf litter) [START_REF] Goldfarb | Differential Growth Responses of Soil Bacterial Taxa to Carbon Substrates of Varying Chemical Recalcitrance[END_REF][START_REF] Purahong | Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition[END_REF]Tláskal et al., 2016). However, whether the addition of complex substrates naturally found across various ecosystems (as roots enriched in structural C compounds) has similar effects on the microorganisms' assemblages (copiotrophs vs. oligotrophs) during microbial succession is still an open question. To assess the importance of substrate quality on the differentiation of both bacterial and fungal communities in terms of copiotrophs/oligotrophs successions, we performed a controlled microcosm incubation experiment with two litters varying strongly in their physicochemical characteristics (maize leaves and roots), an unamended control (without litter) and followed microbial community structure by pyrosequencing at four sampling dates (0, 15, 35 and 91 days). We hypothesized that (i) microbial communities will undergo the copiotrophs/oligotrophs successions for both litters, and (ii) within these successions, copiotrophic and oligotrophic taxa will be more favored by the amendment with maize leaves and roots, respectively.

The soil used for the experiment was a silty loam agricultural soil collected at an experimental research station (Estrees-Mons, northern France). The soil contained 8.70 mg C g -1 soil and a mineral N content high enough to prevent N limitation for the decomposition of both litters [START_REF] Sauvadet | The dynamics of soil micro-food web structure and functions vary according to litter quality[END_REF]. Microcosms were built with soil sampled at a depth of 0-20 cm, with either no litter or 1 cm pieces of maize leaves or roots that were mixed into the soil at a depth of 0-5 cm and a rate of 4.8 g C kg -1 soil mimicking a common crop residue quantity (about 7 t ha -1 ) after the growing season (e.g. [START_REF] Hiel | Impact of crop residue management on crop production and soil chemistry after seven years of crop rotation in temperate climate, loamy soils[END_REF]. The microcosms were incubated at 15°C for 3 months, after which they were destructively sampled at four successive dates: 0, 15, 35 and 91 days later (three replicates by treatment and sampling date). Carbon mineralization was measured in all the incubated microcosms using a CO2 trap (1 M NaOH) titrated by continuous flow colorimetry using an autoanalyzer (TRAACS 2000, Bran and Luebbe). The litter was hand-sorted then washed in water and dried for one week at 37°C before soluble, cellulose, hemicellulose and the Klason lignin contents were measured [START_REF] Sauvadet | The dynamics of soil micro-food web structure and functions vary according to litter quality[END_REF]. The soil bacterial and fungal community structures were determined on soil alone (after leaves and roots were separated) at each sampling date by 454 pyrosequencing using 16S rRNA and 18S rRNA genes, respectively, as described by [START_REF] Terrat | Molecular biomass and MetaTaxogenomic assessment of soil microbial communities as influenced by soil DNA extraction procedure[END_REF]. Diversity analyses were performed on 5000 and 7500 reads for the 16S and 18S rRNA gene sequences of the bacterial and fungal communities, respectively, using the GnS-PIPE pipeline developed for the GenoSol platform (Institut National de la Recherche Agronomique [INRA], Dijon, France).

The microbial communities were then analyzed using the Bioconductor suite package and R software (https://www.bioconductor.org). Dissimilarities between the bacterial and fungal communities of each treatment at each sampling date were first calculated using the Poisson distance at the genus level (after exclusion of genera who were unique across all samples), and then depicted graphically with nonmetric dimensional scaling (NMDS). Significant differences in Poisson distances between amended and unamended treatments were tested by analysis of variance (ANOVA) followed by post hoc tests using Fisher's least significant difference (LSD). In a second phase, we focused on the genera that were the most affected by litter amendments. To do so, the data were log-transformed (rlog function of the DESeq2 R package) to obtain normality and minimize the differences between taxa with low abundances. We then performed a differential expression analysis (DESeq function of the DESeq2 R package) between soil communities that did not receive litter (unamended soil) and soil communities that did receive either leaves or roots at the corresponding sampling date. In this analysis, we considered only the genera that differed significantly in relative abundance from the community in unamended soils (P-value < 0.05 adjusted with Benjamini-Hochberg corrections), which could be distinguished as either enriched (greater abundance than that in the unamended community) or depleted (lower abundance than that in the unamended community).

More details of the DESeq analyses were reported by [START_REF] Edwards | Structure, variation, and assembly of the root-associated microbiomes of rice[END_REF].

The leaf and root additions influenced the structure of both the bacterial and fungal communities at all sampling dates relatively to the unamended soils (Fig. 1a and1b). Poisson distances between unamended and amended treatments were higher with leaves than roots addition for fungal communities at the earliest stage of decomposition (i.e., before 400 mg C kg -1 soil mineralized, Fig. 1d) and for bacterial communities at all sampling dates (Fig. 1c). These results highlight that the structure of bacterial and early-decomposers fungal communities depends directly on substrate quality (Table S1), and confirm previous reports demonstrating that many bacterial and fungal taxa are strongly dependent upon C availability (van der Wal et al., 2013;[START_REF] Purahong | Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition[END_REF][START_REF] Ho | Revisiting life strategy concepts in environmental microbial ecology[END_REF]. This further suggests that taxa feeding on recalcitrant C substrates are closer to communities living in unamended soils than opportunistic taxa feeding on freshly added labile C substrates. On the other hand, fungal community differentiation peak after 15 days of leaf decomposition, suggesting that these early-decomposers (presenting copiotrophic characteristics) could only develop when litter soluble content was high enough (Table S1). Interestingly, only fungal community presented such a peak; we could assume that bacterial differentiation occurred earlier (between 3 and 7 days in [START_REF] Tardy | Land Use history shifts in situ fungal and bacterial successions following wheat straw input into the soil[END_REF], yet our results support that fungi, and not only bacteria, takes an active part in early decomposition process. Further, the constant differentiation level of amended bacterial communities from their unamended counterpart supports the emerging idea that bacterial taxa can be better able to increase with the proportion of complex C compounds than previously thought [START_REF] Rousk | Fungal and bacterial growth in soil with plant materials of different C/N ratios[END_REF][START_REF] Rousk | Revisiting the hypothesis that fungal-to-bacterial dominance characterizes turnover of soil organic matter and nutrients[END_REF]. However, as expected, high level of soluble C favor the differentiation of bacterial taxa which may also feed on products originating from fungal degradation [START_REF] Purahong | Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition[END_REF]Tláskal et al., 2016).

When studying microbial community composition, we found that only 6 out of 59 genera (e.g., Arthrobacter or Variovorax for bacterial community, Table S2) and 11 out of 57 genera (e.g., Ascobulus or Heterobasidion for fungal community, Table S3) were impacted by both litter types (Fig. 2).The idea that many microbial genera depend upon substrate quality is reinforced by the low redundancy between microbial genera at different sampling dates (Fig. 2); only a few bacterial genera remained enriched at all sampling dates (e.g., Pseudomonas during both leaves and roots decomposition, Table S2) and no fungal genus was consistently enriched or depleted over time (Table S3). These results highlight the strong specificity of microbial genera to both litter quality and decomposition stage, which is partly overlooked when focusing only at the phylum level. Indeed, the bacterial genera impacted during litter decomposition belonged mainly to the three same phyla (i.e., Proteobacteria, Bacteroidetes and Actinobacteria), which are often regarded as copiotrophic in the literature [START_REF] Ho | Revisiting life strategy concepts in environmental microbial ecology[END_REF]. However, most phyla as Proteobacteria, had both enriched (e.g., Variovorax) and depleted genera (e.g., Geobacter) after litter additions, and this regardless of litter quality or sampling date (Table S2). This clearly indicates that different taxa within a phylum may present contrasting metabolic status. This further underscores the limits of the copiotroph-oligotroph model at the phylum level and the necessity to work at a finer taxonomic resolution [START_REF] Philippot | The ecological coherence of high bacterial taxonomic ranks[END_REF][START_REF] Purahong | Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition[END_REF][START_REF] Ho | Revisiting life strategy concepts in environmental microbial ecology[END_REF].

We conclude that high quality substrate induces greater differentiation of early decomposers fungal communities and bacterial communities than low quality substrate. Further, both early-and late-decomposers showed a strong specificity to litter quality and decomposition stage at the genus level. Our results challenge the traditional concept of bacterial/fungal shift during decomposition and underline the necessity to identify more accurately life strategies of soil microbes at different taxonomic levels in order to improve our understanding of structure-function relationships and the role of microbial communities in ecosystem functions such as C mineralization and decomposition rates. Tláskal, V., Voříšková, J., Baldrian, P., 2016. Bacterial succession on decomposing leaf litter exhibits a specific occurrence pattern of cellulolytic taxa and potential decomposers of fungal mycelia. FEMS Microbiol Ecol 92. van der Wal, A., Geydan, T.D., Kuyper, T.W., de Boer, W., 2013. A thready affair: linking fungal diversity and community dynamics to terrestrial decomposition processes. FEMS Microbiol. Rev. 37, 477-494. S1. Significant differences between all sampling dates and litters were tested by ANOVA followed by post hoc Fisher tests and are represented by different letters for each graph.

Figure captions

Fig. 1 .

 1 Fig. 1. Microbial community structure during the experiment represented by NMDS

Fig. 2 .

 2 Fig. 2. Phylum identification of the enriched and depleted genera with maize leaf or

  Fig.1

Acknowledgments. The present study was funded through INRA, the Department of Environment and Agronomy, and the SOFIA project (ANR Agrobiosphere, ANR-11-AGRO-0004), which provided a doctoral grant to M. Sauvadet. The authors thank P-A. Maron and the UMR Agroécologie team for their help with molecular analyses and interpretation as well as G. Alavoine, S. Millon, O. Delfosse, C. Leminhbach and V.

Nowak for their assistance during the experiment.


Karima Mehaoued
email: karima_mehaoued@yahoo.fr

Berangere Lartigue
email: berangere.lartigue@univ-tlse3.fr

Influence of a reflective glass façade on surrounding microclimate and building cooling load: Case of an office building in Algiers

Keywords: reflective glass façade, microclimate, urban heat island, cooling load, building surface temperature Highlights

Introduction

In Algeria, the building sector is the largest consumer of energy among all economic sectors, accounting for 42% of the total energy. The building energy consumption has increased by over 30% over the last 30 years and this trend will continue through 2030 [1]. Additionally, the lack of land in urban sites has led to a proliferation of tall buildings since the 1990s, and most of them use curtain-wall to enhance their aesthetics. Typically, these glass surfaces are reflective, and incident solar radiation is largely reflected. They reach a reflectance of about 30-90% in order to reduce the cooling load [START_REF] Button | Glass in Building[END_REF], [START_REF] Yuan | Geometrical-optics analysis of reflective glass beads applied to building coatings[END_REF]. Yet, the reflected sunbeams not only cast surplus light [START_REF] Yang | Simulation of reflected daylight from building envelopes[END_REF], [START_REF] Danks | Assessing reflected sunlight from building facades: A literature review and proposed criteria[END_REF], but also add a supplementary thermal load to the neighboring environment [START_REF] Nagahama | Optical properties and field test results of spectrally-selective solar control window film that enables not increasing downward reflection[END_REF].

At building scale, several studies have addressed the effect of the envelope on the energy performance of buildings based on the percentage of glass façade and its thermoradiative properties. Barbosa and Ip [START_REF] Barbosa | Perspectives of double skin façades for naturally ventilated buildings: A review[END_REF] and Pomponi et al. [START_REF] Pomponi | Energy performance of double skin façades in temperate climates: A systematic review and metaanalysis[END_REF] have shown that highly glazed façades, if designed carefully, such as double skin façades, can exhibit significantly better behavior than conventional windows. Indeed, the exterior walls respond dynamically to varying ambient conditions, and can incorporate a range of integrated sun-shading, natural ventilation, and thermal insulation strategies.

Yet, if they are poorly designed, they not only increase the building energy consumption, but also affect the occupants' thermal comfort, due to the thermal radiation coming from the hot glazing surfaces. Other authors are interested in the effect of the glass types and their ratios to the wall surface (Window to Wall Ratio, WWR) on the energy performance of indoor spaces. For example, Bouden [START_REF] Bouden | Influence of glass curtain walls on the building thermal energy consumption under Tunisian climatic conditions: The case of administrative buildings[END_REF] investigates the impact of glass façades on annual cooling and heating loads in the Mediterranean climatic conditions of Tunisia. His set of cases consist of seven types of glass and five window to wall ratios. He shows that glazed façades, according to their types and orientation, can provide lower annual energy load than the currently used 20%-WWR masonry wall buildings with single glazed window. The optimal results are found for a 90%-WWR, with a curtain wall made of one clear and one reflecting panes. Lartigue et al. [START_REF] Lartigue | Multi-objective optimization of building envelope for energy consumption and daylight[END_REF] provide a methodology for optimizing the envelope of a building with respect to a triple objective of heating load, cooling load and daylight. The optimized variables are the WWR and thirteen window glass types characterized by their visual and thermal characteristics (visual and solar transmittance and U-value). This method offers the advantage of quickly and accurately giving the optimal solutions of the problem, providing guidelines for construction decision.

However, these studies do not take into account the effect of buildings on the microclimate, which is a significant factor in the building energy consumption. In fact, Yuan et al. [START_REF] Yuan | A study on the durability of a glass bead retroreflective material applied to building facades[END_REF] affirm that half of the city's anthropogenic heat results from buildings.

At urban scale, the microclimate is influenced by the heat island phenomenon (Urban Heat Island, UHI), which has a direct impact on the thermal comfort in the building, as well as on the energy demand. If in winter the effect can be positive by reducing heating consumption, in summer airconditioned buildings increase their energy consumption. Some studies highlight the important impact of the UHI on ambient air temperature differences between urban and rural areas, as well as its implications on the building energy performance [START_REF] Kotharkar | Evaluating urban heat island in the critical local climate zones of an Indian city[END_REF], [START_REF] Zinzi | On the relation between urban climate and energy performance of buildings, A three-year experience in Rome, Italy[END_REF]. Santamouris et al. [START_REF] Santamouris | On the impact of urban climate on the energy consumption of buildings[END_REF] use the survey of thirty weather stations of urban climates in Athens, Greece, in order to simulate the heating and cooling loads of a reference building. They note that the impact of high air temperature in the city is extremely important and can double the cooling load peak of the building under consideration. Toparlar et al. [START_REF] Toparlar | Impact of urban microclimate on summertime building cooling demand: a parametric analysis for Antwerp, Belgium[END_REF] compute buildings' cooling demands in three locations, in Antwerp, Belgium: a rural location; an urban location, away from an urban park; and another urban location, close to the same park. They combine two building types and six sets of construction characteristics. They show that buildings with better thermal insulation and lower infiltration rates increase the cooling demand by 48% once moved from the rural location to an urban location.

Residential buildings close to the park are found to have on average 13.9% less cooling demand, compared with buildings away from the same park. Bozonnet et al. [START_REF] Bozonnet | Modeling solar effects on the heat and mass transfer in a street canyon, a simplified approach[END_REF] study by CFD simulations the interaction between urban microclimate and energy demand for air conditioning in a typical case of a street canyon, taking into account anthropogenic dissipation of air conditioners on façades.

They show that the computed building energy consumption in summer could be more than 30% higher if calculated with the street canyon air temperature rather than the weather station temperature. Bouyer et al. [START_REF] Bouyer | Microclimatic coupling as a solution to improve building energy simulation in an urban context[END_REF] evaluate the energy demand of one building in a district in Lyon, France, over one week in winter and one week in summer. They study the impact of two types of urban landscape, a full-mineralized one and a vegetated one. They show that the vegetated case leads to 9% reduction in cooling energy demand compared to the mineralized one. Mirzaei et al. [START_REF] Mirzaei | Urban neighborhood characteristics influence on a building indoor environment[END_REF] study the surrounding radial areas of buildings that impact the indoor temperature to propose a method for forecasting it.

In fact, the material composition of urban surfaces is a crucial parameter in the development of microclimates inside the cities, thereby also affecting energy use in buildings [START_REF] Park | Energy performance of analysis of variable reflectivity envelope systems for commercial buildings[END_REF]. Built environment modifies solar incidence, while material properties affect the energy balance of surfaces. Several experimental and numerical studies ( [START_REF] Santamouris | Using advanced cool materials in the urban built environment to mitigate heat islands and improve thermal comfort conditions[END_REF], [START_REF] Alchapar | The use of reflective materials as a strategy for urban cooling in an arid "OASIS" city[END_REF], [START_REF] Santamouris | Cooling the cities -A review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments[END_REF] and [START_REF] Rossi | Analysis of retroreflective surfaces for urban heat island mitigation: a new analytical model[END_REF]) have shown the effectiveness of using reflective materials for roofs and pavements. They dissipate solar radiation and mitigate the effects of the UHI. Yet, when reflective materials are used in façades, multireflections of sun's rays with surrounding surfaces create a radiative trapping that increases air temperatures and energy consumption of buildings. Danks et al. [START_REF] Danks | Assessing reflected sunlight from building facades: A literature review and proposed criteria[END_REF] have shown that high reflectance of reflective glass raises the surface temperatures of the surrounding spaces (façades, parks, sidewalks and roof tops). Consequently, they propose to limit the reflected irradiance of façades to 1500 W/m². Lately, in order to reflect the solar radiation beyond the urban canopy, Nagahama et al. [START_REF] Nagahama | Optical properties and field test results of spectrally-selective solar control window film that enables not increasing downward reflection[END_REF] developed a façade material that achieves thermal comfort of both indoor and outdoor spaces. To do so, the authors propose a transparent solar control window coating that reflects near-infrared rays to the sky. Its microstructure enables to return infrared rays to the sky. Other researchers such as Rossi et al. [START_REF] Rossi | Analysis of retroreflective surfaces for urban heat island mitigation: a new analytical model[END_REF] and Yuan et al. [START_REF] Yuan | Application of glass beads as retroreflective facades for urban heat island mitigation: Experimental investigation and simulation analysis[END_REF] also show that retro-reflective materials, applied as coatings on urban paving and building envelopes, can effectively mitigate urban heat island.

Yet, to our knowledge, no study has been performed specifically to evaluate the impact of the façades reflectance on both outside and inside building environment. In this article, we are studying experimentally and numerically the microclimate around an existing reflective glass building in Algiers, Algeria, as well as the impact of the microclimate on the building energy cooling load.

Case study: a glass office building in Algiers

Location

The case study is an existing reflective glass office building located in Algiers, the biggest city in Algeria in terms of inhabitants and urbanization growth. It is located on the Mediterranean coastline at 36°.43 northern latitude and 3°.15 longitude. It has a Mediterranean climate where summers are hot and wet, while winters are cold and short, with rains from 400 to 1000 mm per year, and with more than 250 sunny days per year and 16 hours of sunlight per day.

The building is surrounded by a nine-story office building in the North-East, with a white façade; by four villas of two levels each in the South-East; by an apartment building of four levels in the South-West, and another office building of five levels in the North-West. The adjacent horizontal surfaces are asphalt roads. Figure 1 shows the ground plane of the case study building and its surroundings.

Figure 2 shows the evolution of monthly maximal temperatures averaged over 29 years from 1981 to 2010, in Algiers [25]. From the graph, the highest temperature is 31.8°C and it is recorded in August, the hottest month of the year. According to the National Office of Meteorology of Algeria, the rise in temperatures has affected the entire country. Recent heat waves (2012,2015) overwhelmed the country with temperatures reaching 47°C in the shade and 54°C in the sun. These elevated temperatures increase the peak of the electric demand for air conditioning, which leads to possible decreases in voltage on the electrical networks. This increased our interest in investigating the cooling load of the case study building.

Building envelope

Inhabited since 1999, the building under consideration is composed of three blocks (9, 10 and 11 floors) and one central courtyard in each block. Its dimensions are 132 m in length, 56 m and 32 m in maximal and minimal widths, and three different heights of 38 m, 35 m and 32 m (Figure 3). The volume to be air-conditioned is 206 720 m 3 . The global floor plan of 2 756 m² has a rectangular shape with two kinds of offices: peripheral with view on the exterior, and central with view on the courtyard. The glass used for this building reflects a large part of sunlight. The selective action of the coating used in the reflective layer has the effect of preventing the solar heat from entering the building by reflecting light and infrared radiation (Figure 4, above and below).

Figure 5 shows the optical characteristics of the glass. A significant reflection (20-35%) is observed in the region of the visible light and a low transmission (15-20%) of ultraviolet. The transmission peaks near the orange part of the visible region (the glass appears brown in transmission from the inside) and is blue in reflection because the reflection curve peaks around the blue band of the visible spectrum [START_REF] Button | Glass in Building[END_REF]. The reflective glass has a solar reflectance of around 0.32 for our case of reflective blue glass. The low transmission of the visible radiation (a maximum of about 20%) requires the use of artificial lighting all day and all year long.

Methodology

Figure 6 summarizes the methodology of the study. The microclimate around an existing reflective glass building in Algiers has been investigated experimentally and numerically (Figure 6.a). Then, the study of the impact of the microclimate on the cooling energy load of such a glazed building has been conducted (Figure 6.b). To do so, we have computed with the software Ecotect the cooling load of the building using three different weather files: one from the weather station located at the airport far from the building (Case 1), another issued from a micro-station located on the roof of the building (Case 2), and the last one computed with the microclimate ENVI-met software, taking into account the building envelope and its surroundings (Case 3).

Experimental data

The experiments have been conducted during a typical summer day, on 2 nd August 2013. It was a clear and sunny day, with no wind.

Weather data measured by a micro-station on the roof

A Hobo weather micro-station was used to measure the air temperature, the relative humidity and the wind speed. Table 1 describes the characteristics of the sensors. The micro-station was located on the building roof, and the data were recorded during the representative day (2 nd August 2013).

Thermograms of the façades

To characterize the microclimate surrounding the glazed building, we have taken thermograms of the four façades using a thermographic camera. The characteristics of the instruments are reported in Table 1. The thermograms have been recorded three times during the day, at 9:00, 12:00 and 15:00, on the four façades.

Weather data measured at 2 m from the ground

The software ENVI-met is able to compute the microclimate around the building, taking into account the effect of the reflective glass of the building façades and the district configuration. To do so, the air temperature, the relative humidity and the air speed have been measured at 2 m from the ground, by a mobile hygro-thermometer, whose characteristics can been found in Table 1. These values are used as input for ENVI-met. The data were recorded once, at 7:00, quite far from the surrounding buildings as recommended by ENVI-met. The position of the measurements is indicated on Figure 7.

Modeling of the microclimate using ENVI-met

The experimental measures give precious local information on the microclimate surrounding the building. Yet, they are not sufficient to provide an extensive characterization of the close outdoor environment. ENVI-met is able to provide data all around the building, taking into account the reflective envelope and the district configuration.

Description of the software

ENVI-met V4.0 is a 3D prognostic microclimate model based on computational fluid dynamics and thermodynamics. The software simulates airflow around buildings, heat and vapor exchanges, energy and mass exchanges between vegetation and its surroundings [START_REF] Bruse | The influences of local environment design on microclimate -Development of a prognostic numerical Model ENVI-met for the simulation of wind, temperature and humidity distribution in urban structures[END_REF].

To simulate the microclimate, ENVI-met requires some input parameters such as weather conditions, urban structure and physical properties of the urban surfaces and vegetation. The computed climatic variables include direct/diffuse solar radiation, long wave radiation, and vertical profile of atmospheric parameters (air temperature, air velocity, and air humidity) calculated from 0 to 2500 m above ground.

For the simulation, the three-dimensional building envelope is divided into 3D parallelepipedic grid cells with the dimensions (x), (y) and (z). The horizontal spacing (x) and (y) is constant for all grid cells. In a vertical grid, all grid cells have the same height (z) -except the lowest grid cells that are divided into five sub grid cells so that the vertical height of these grid cells is 0.2(z). The vertical higher resolution of the grid cells closer to the ground leads to higher accuracy and has the advantage that the exchange processes between atmosphere and ground, which have a substantial influence on the microclimate at ground level, can be simulated more accurately [27].

ENVI-met has been verified with field experimental data by many researchers. In [START_REF] Huttner | Further development and application of the 3D microclimate simulation ENVI-met[END_REF] and [START_REF] Huttner | Strategies for mitigating thermal heat stress in central European cities: the project KLIMES[END_REF],

Huttner validates the use of ENVI-met by implementing an enhanced module for the calculation of the fluxes of energy and temperature within façades and roofs. He shows the good agreement between the temperatures measured on the roof and the simulated values. Other studies [START_REF] Krüger | Impact of urban geometry on outdoor thermal comfort and air quality from field measurements in Curitiba, Brazil[END_REF], [START_REF] Yang | An integrated simulation method for building energy performance assessment in urban environments[END_REF], [START_REF] Ali-Toudert | Energy efficiency of urban buildings: significance of urban geometry, building construction and climate conditions[END_REF] evaluate the impact of the street geometry on the ambient temperatures and on pedestrian comfort levels. They show the good agreement between field measurements and comfort surveys with urban climate simulations using ENVI-met.

Simulation settings

The case study implemented for the present analysis is an office building located in a densely urbanized area in the center of Algiers. The settings of the ENVI-met simulations are presented in Table 2. A study of the grid sensitivity has been implemented. The microclimate along one façade has been computed with a tighter mesh of dx = dy = dz = 0.5 m, instead of 2 m. The results of the air temperature profiles for the two meshes, according to the height are given in Table 3. The temperature profiles follow the same tendency, with values slightly higher for the actual mesh. The maximum difference reaches 0.5°C. This gap is in the range of the experimental uncertainty (between 0.2°C and 0.5°C in Table 1). Due to a lower computation time, the mesh of dx = dy = dz = 2 m has been chosen.

In our study, the data measured on site by the hygro-thermometer, at 2 m from the ground, are entered in ENVI-met as input, to simulate the microclimate around the case study building, as explained above in § 3.1.3. The outdoor microclimate parameters are calculated in specific points called receptors. Figure 7 shows the horizontal positions of the 7 receptors that were chosen around the building, 4 (R) at 1 m in front of each façade and 3 (P) inside the atria. Three floors of the building were investigated: ground (H=1.80 m), middle (H=17.00 m) and top floors (H=31.00 m), as seen in Figure 8 3

.3 Modeling of the energy load using Ecotect

To show the impact of the microclimate on the indoor thermal environment of the building, we have computed the cooling load according to three weather data files.

Description of the software

The building cooling load is calculated with the software Ecotect. Ecotect is an environmental analysis tool with a wide range of performance analysis functions such as thermal analysis, solar exposure, acoustics, lighting and shading. It gives optimal solutions for the existing construction and proposes modifications to new designs for improved energy performance [START_REF] Sanusi | ECOTECT Analysis: Integration of Architectural Studio Project with Theory Classroom Assignment through Computer Simulation[END_REF], [START_REF] Trisnawan | Ecotect design simulation on existing building to enhance its energy efficiency[END_REF]. Ecotect uses CIBSE Admittance Method (Chartered Institution of Building Services Engineers) to estimate the heating and cooling loads for the thermal zones of a given building.

The Ecotect weather tool provides a psychometric chart to determine the comfort zone of each region, and can provide optimal analysis corresponding to various passive strategies according to local weather characteristics [START_REF] Yang | Application Research of Ecotect in Residential Estate Planning[END_REF]. It can also analyze the solar radiation, and calculate the best orientation for buildings. Many studies use this software to analyze energy loads for different systems such as air conditioning, energy saving especially from solar heat, day-lighting and natural airflow, and for many existing or new buildings [START_REF] Trisnawan | Ecotect design simulation on existing building to enhance its energy efficiency[END_REF], [START_REF] Yang | Application Research of Ecotect in Residential Estate Planning[END_REF], [START_REF] Ali | A Comparative Study of ECOTECT, EnergyPlus&DAIlux (Building Energy Lighting Simulation) tools[END_REF], [START_REF] Ryan | Validation of building energy modeling tools under idealized and realistic conditions[END_REF], and [START_REF] Fallahtafti | Optimisation of building shape and orientation for better energy efficient architecture[END_REF].

Simulation settings

One of the objectives of our study is to show the impact of the microclimate on the energy performance of the glazed buildings. We have therefore considered three microclimates, by creating three weather data files with Ecotect. The cooling load of the case study building is calculated with the resource consumption function, for one typical summer day. The three microclimates investigated are used as weather files in Ecotect. The building in Ecotect is divided in 7 thermal zones at each level. Figure 9 shows the seven thermal zones chosen for the simulation. Four thermal zones correspond to the four orientations of the building, and the three others correspond to the three atria. In Cases 1 and 3, there is only one weather file for the 7 thermal zones. In Case 3, the cooling load is calculated with the weather file simulated at its closest receptor. The horizontal positions of the 7 receptors are given in Figure 7. The details of the simulation settings are given in Table 4.

Results and discussion

Experimental façades temperatures

To better understand the thermal effects of coated glass curtain walls in an urban context, thermograms have been performed to analyze the wall surface temperatures. Figure 10 shows the surface temperature of the four glazed façades, for three sequences of the representative summer day of 2 nd August: 9:00, 12:00 and 15:00. The wall surface temperatures, measured using a thermographic camera, show significant variations between the different façades for the 3 sequences. The marked values on Figure 10 are the temperatures measured in the center of the picture. The surface temperatures depend obviously on the orientation.

Building surface temperature vs. time

The North-East façade shows a maximum surface temperature of 44.4°C in the morning at 9:00. This is due to the incident radiation after sunrise. The surface temperatures decrease and reach 27.7°C at 12:00 and 30.6°C at 15:00 when the sun is far from this façade. That increase at 15:00 can be explained by the reflectance of the façade of the opposite 9-level building (Figure 1). That building has a white façade.

On the South-East façade, the thermogram shows a maximum value of 48.4°C at 12:00 due to the incident radiation. At 9:00, the temperature measured is 34.9°C, due to the sun exposure. At 15:00, the temperature decreases because the façade is hidden from the sun.

For the South-West side, the first heating effects appear at the third sequence of the day with more significant values according to the North-East and South-East façades. Indeed, at 15:00, the maximum surface temperature reaches 55.4°C. Due to the sun exposure, the façades temperatures become very high and cause the atmosphere to warm up. During the morning at 9:00, the South-West façade displays the lowest surface temperature of 18.8°C because it is shaded until 12:00 when it receives solar energy from the Zenith and reaches 28.9°C.

At the first hours of the day, the North-West façade does not receive direct solar radiation at all, so its surface temperatures are 20.7°C at 9:00 and 28.5°C at 12:00. In the afternoon, a temperature of 39.0°C is recorded at 15:00.

As mentioned above, the absorption coefficient of the glass façade is around 40%. This can be seen on Figure 5. This absorption increases significantly the surface temperatures. Then, the envelope emits IR radiation to the inside and outside environments.

Building surface temperature vs. height

Several pictures on Figure 10 show the evolution of the surface temperature with the height. It can be seen that the temperature decreases with height, particularly on the North-East façade all day long, but also on the South-East and South-West façades at 15:00, and at the North-West façade at 12:00. The top of the building is cooler than the lower levels. This is explained by the dihedral effect. The façades in contact with the horizontal surface (asphalt road) create a dihedral effect [START_REF] Lehtihet | Evaluation of microclimatic effects on urban sites by means of in situ measurements, thermographic study and numerical simulation[END_REF], which allows heat exchange between the two adjacent surfaceshorizontal and vertical. Therefore, there is an additional heat received by the lower levels of the building, coming from the reflection on the asphalt. These heat exchange effects have a key role in the warming of the air. In our case study, the building is surrounded by asphalt roads (Figure 1). Priyadarsini et al. [START_REF] Priyadarsini | Microclimatic modeling of the urban thermal environment of Singapore to mitigate urban heat island[END_REF] and Gros et al. [START_REF] Gros | Cool materials impact at district scale -Coupling building energy and microclimate models[END_REF] also showed in numerical and experimental studies the decrease of the surface temperature with the height of the building. Both of them explain the higher temperatures at the lower levels by the proximity of the road surface, which increases the air temperature and therefore, the surface temperature of the building by convection heat transfer.

Computed microclimate around the building

The microclimate around the building is modeled with ENVI-met.

Figure 11 compares air temperatures around the building for the three different levels showed on Figure 8. It is observed that the highest air temperatures occur at the lowest level 1.80 m. Then, the temperature decreases with height, reaching an average of 34°C at H=17 m and 33.3°C at H=31 m.

The lowest levels of the building are impacted by the horizontal surface of the asphalt road. A lot of studies have highlighted the strong influence of asphalt on the heat exchanges [START_REF] Allegrini | Influence of the urban microclimate in street canyons on the energy demand for space cooling and heating of buildings[END_REF]. For example, Chatzimitriou and Yannas [START_REF] Chatzidimitriou | Microclimate development in open urban spaces: The influence of form and materials[END_REF] tested different horizontal materials and showed that, with an albedo of 0.15, the hottest surface's material is asphalt. The multiple reflections between the building's façade and the asphalt lead to an increase of the air temperature at the lower levels, which is relevant with the same tendency recorded by the experimental thermograms on the building surface temperatures.

For the atria, the mean air temperature ranges between 34.0°C for the first level, 33.7°C for the second level, and 33.5°C for the third level. The hottest atrium is the smallest one because of the entrapping of solar radiation. These results show the impact of the reflectance of the building glass façade on the surrounding microclimate due to the multiple reflections between the façades and the ground, with the presence of dihedral effects [START_REF] Lehtihet | Evaluation of microclimatic effects on urban sites by means of in situ measurements, thermographic study and numerical simulation[END_REF], leading to higher air temperatures.

In order to compare the measured air temperatures with the computed ones, the temperatures calculated by ENVI-met at the outdoor receptors (R) near the 4 façades are studied in detail. The receptors are located at a distance of 1 m from the building façades according to the four orientations (NE, SE, SW and NW) and can be seen on Figure7.

Figure 12 shows the evolution of the air temperatures vs. time, both for the experimental temperatures and computed ones. The experimental temperatures are the ones measured at the reference station (Ref-St) and the ones measured by the micro-station on the roof (Roof). The computed temperatures are the ones calculated at the four orientations, at the height of H=1.80 m.

From 8:00 to 20:00, the experimental temperatures are lower than the computed ones, the lowest being the temperatures measured at the weather station. This is understandable since the weather station is located far from the city center, and therefore does not measure the effect of the urban heat island.

The air temperature measured on the roof is globally higher than the air temperature measured at the reference station, especially starting from noon. The micro-station on the roof actually takes into account the microclimate due to the reflective glass building.

At last, the air temperatures computed by ENVI-met are higher than the measured ones, all along the day. The temperatures calculated on the East façade (NE and SE) are logically the highest in the morning, while the ones calculated on the West (NW and SW) façade are higher in the afternoon.

That shows the effect of the microclimate, taken into account in the modeling, due to the reflective glass building.

Impact of the microclimate on the cooling load of the building

After having shown the impact of the glazed building on its surrounding microclimate, we have conducted a study to quantify the impact of the microclimate on the cooling load. The modeling of the cooling load has been performed with Ecotect. The cooling energy load of the building is calculated for the typical summer day of 2 August, for three microclimates (Cases 1, 2, and 3). The cooling loads are computed in the 7 thermal zones shown in Figure 9, and for 3 levels (Figure 8).

For the three cases, the first step is to create the weather files with Ecotect. According to the cases, they are either measured by the weather station (Case 1), the micro-station on the roof (Case 2), or computed by ENVI-met (Case 3). In this last Case 3, the weather file is created from the climatic data calculated at the 7 receptors (R and P, on Figure 7), and for the 3 heights. A total of 21 weather files have been generated to calculate precisely the cooling load at the 21 thermal zones.

Figure 13 shows the average cooling load during the air-conditioned time period (8:00-20:00), for the three microclimates. As expected, the highest cooling load is obtained in the Case 3, corresponding to the microclimate computed with ENVI-met. This microclimate takes into account the urban heat island due to the reflective glass building, and therefore the air temperature is higher than for the other weather files (Figure 12). The cooling load calculated in Case 2 with the measured weather data on the roof is 8% lower. Indeed, the micro-station measures the urban microclimate, but only on a localized position, on the roof, and cannot precisely take into account the impact on the air temperature of the vertical reflections of the building. At last, the lowest cooling load is calculated in Case 1, with the data measured at the reference station far from the building. The value is 15% lower than Case 3.

The results show the significant impact of the microclimate on the energy demand, which is strongly affected by the amount of solar radiation reaching the building surface. They are in agreement with other studies in the literature, that have shown the impact of the microclimate on the energy demand such as [START_REF] Toparlar | Impact of urban microclimate on summertime building cooling demand: a parametric analysis for Antwerp, Belgium[END_REF], [START_REF] Bozonnet | Modeling solar effects on the heat and mass transfer in a street canyon, a simplified approach[END_REF] and [START_REF] Bouyer | Microclimatic coupling as a solution to improve building energy simulation in an urban context[END_REF].

Conclusion

The impact of a reflective glass building on its outdoor and indoor environment is investigated in the city of Algiers, Algeria. The outdoor environment has been studied experimentally and numerically. A weather micro-station has been installed on the building's roof, and thermograms have been recorded to measure the surface temperature of the building. Some weather data measured by a mobile thermo-hygrometer allow the computing of the microclimate surrounding the building with the software ENVI-met. It is found that the high surface temperatures of the building increase the nearby air temperature. The computed air temperatures around the building are higher than the measures performed on the roof, followed by the ones from the city weather station at the airport. Both the experimental measures (through the thermograms), and the ENVI-met computed microclimate with ENVI-met, show that the air temperature decreases with the building height. This is due to the dihedral effect that occurs on the ground, between the hot asphalt and the low levels of the building.

The cooling load of the building has been calculated with the software Ecotect, with the three weather files. The cooling load calculated with the computed microclimate is 8% higher than the one calculated with the measured data from the roof, and 15% higher than the one calculated with the city weather station. When it is not considered, the urban heat island effect leads to an important underestimation of the cooling demand.

Even if reflective glass façades are conceived to decrease the entering solar radiation, in hot climates such in Algeria, they tend to notably increase the surrounding air temperature. That ultimately increases the building cooling load, in addition to causing outdoor visual glare.

Use of reflective glass with high reflectance is found to have a serious thermal impact by increasing the external air temperature and the energy cooling load. To evaluate this cooling load, calculation of the accurate microclimate around the building seems to be necessary. Future work will conduct a sensitivity analysis to take into account all the impacting parameters such as the thermal and optical properties of the glass, the district configuration and the orientation, on the energy demand of the building.

Case 1 -Case 3 -

 13 Reference weather station (referred as Ref-St): this file uses meteorological data measured by the reference station of the city, located at the airport, 25 km from the city center of Algiers. The data of 2 nd August 2013 have been used to create the weather file for the simulation. Case 2 -Micro-station on the roof (referred as Roof): these data capture part of the microclimate as they have been recorded on the roof of the building. Yet, they are very localized and do not capture the temperatures along the façades. Modeling of the microclimate with ENVI-met (referred as ENVI-met): uses weather data computed by the ENVI-met microclimate software. This modeling is based on experimental mobile measurements as explained above.

Figure 1 .

 1 Figure 1. Ground plane of the building and its surroundings

Figure 2 .Figure 3 .

 23 Figure 2. Monthly maximal temperatures averaged over 29 years from 1981 to 2010 (from [25])

Figure 4 .Figure 5 .Figure 6 .Figure 7 .

 4567 Figure 4. The case study building from the outside (above) and the inside (below)

Figure 8 .Figure 9 .Figure 10 .Figure 11 .Figure 12 .Figure 13 .

 8910111213 Figure 8. Vertical section showing the three levels considered for the cooling load calculation

Table 3 .

 3 Difference in air temperature profiles according to the two tested meshes

	Hour	Height (m)	Air temperatures (°C) Actual mesh Tight mesh	∆T
		1.4	23.4	23.0	0.4
	08:00	17	24.1	23.7	0.4
		31	24.5	24.1	0.4
		1.4	26.2	25.8	0.4
	09:00	17	26.2	25.8	0.4
		31	26.1	25.7	0.4
		1.4	27.8	27.4	0.4
	10:00	17	27.7	27.3	0.4
		31	27.5	27.1	0.4
		1.4	29.2	28.8	0.4
	11:00	17	28.9	28.5	0.4
		31	28.6	28.2	0.4
		1.4	30.7	30.3	0.5
	12:00	17	30.3	29.8	0.5
		31	30.0	29.5	0.4
		1.4	32.2	31.7	0.5
	13:00	17	31.7	31.2	0.5
		31	31.3	30.8	0.5
		1.4	33.6	33.1	0.5
	14:00	17	33.0	32.5	0.5
		31	32.6	32.1	0.5
		1.4	34.7	34.2	0.5
	15:00	17	34.2	33.6	0.5
		31	33.6	33.1	0.5
		1.4	35.4	34.9	0.5
	16:00	17	34.8	34.3	0.5
		31	34.3	33.7	0.5