Full scale experimentation on a new translucent passive solar wall combining silica aerogels and phase change materials

Abstract

International audienceThis paper presents the first passive solar wall providing simultaneously super insulation, heat storage and daylighting to the inner space. The wall’s external layer is composed of a silica aerogels bed for high insulation and solar radiation transmission. The second layer, internal, is composed of glass bricks filled with a eutectic phase change material (PCM) for heat storage and restitution. The whole wall is translucent. The experimentations carried out to characterize thermal and optical properties of the materials used are described. Then results are given for a full scale comparative experimentation on a twin zones building located in the south of France for the solar wall and a standard opaque high thermal capacity wall. Results show the heat losses through the wall are very low while the heat and light gains are high: The U value of the solar wall is 0.59 W m−1 K−1 and 0.72 W m−1 K−1 respectively when the PCM is in liquid and solid state. With the test building in free floating condition, the temperature difference between the outdoor and indoor air provided by the wall is about 9 °C in winter. The wall can provide up to 500 lux to the inner environment, which is sufficient for conference rooms. The tested wall has proven more effective in winter and shoulder season, particularly for cold sunny climates, but may cause overheating in summer

A study on the effect of ground surface boundary conditions in modelling shallow ground heat exchangers

“…For example, an experimental study carried out on a novel translucent full scale passive solar MEPCM wall by Berthou et al (Berthou et al, 2015) revealed that it could be used to provide significant improvement of indoor temperatures in both cold and sunny climates. Silva et al (Silva et al, 2015) evaluated the thermal performance of a novel PCM window shutter in a room and obtained a reduction in the maximum and minimum peak temperatures by 6% and 11% respectively.…”

Preparation and performance of novel form-stable composite phase change materials based on polyethylene glycol/White Carbon Black assisted by super-ultrasound-assisted

“…On the other hand, silica has been extensively investigated in the fields of PCMs and heat storage. Berthou [23] has formed a new translucent passive solar wall by combining silica aerogels and PCMs; Min [2] has investigated PEG/mesoporous-silica-shape-stabilized PCMs; Chen [24] has utilized hydrophobic fumed silica for preparing form-stable composite PCMs; Qian [5] and He [25] have prepared shape-stabilized PEG/SiO 2 composites by sol-gel methods.…”

Phase Change Materials in Transparent Building Envelopes: A Strengths, Weakness, Opportunities and Threats (SWOT) Analysis

“…• the geographical distribution of the studies, which also provides an indication of the climatic conditions of the study; • the climatic/seasonal distribution of the studies: winter season (37%) [12][13][14][15][16][17][18][19][20][21][22], mid-season (10%) [14,15,20] and summer (50%) [13][14][15][16][17]20,[23][24][25][26][27][28][29][30][31] season periods; • the most investigated PCM typologies, that have been found to be paraffin wax (60%) [14][15][16]18,19,22,23,[25][26][27][28][29][30][31][32][33][34][35] and salt hydrates (20%) [12,13,…”

“…• in all the papers, the PCM had been macro-encapsulated in containers, that is, glass containers (70%) [12][13][14][15][20][21][22][23][24][25]27,[30][31][32][33][34][35][38][39][40][41], polycarbonate containers (20%) [16,17,19,28,36,42] and aluminium containers (10%) [18,26,29]; • the technologies had predominantly been characterised in outdoor test cells (57%) [14,15,17-22, 24-27,29,31,35] and through laboratory analysis (53%) [12,13,17,20,23,[32][33][34][35][36][37][38][39][40][41][42], while some other studies had been carried out by coupling a modelling activity with an experimental activity (37%) …”

“…Berthou [20] prototyped a system in which PCM was combined with aerogel in order to achieve the aims of superinsulation, heat storage and daylighting. The results of laboratory and in situ experimentations showed that the translucent layer of silica aerogel played a filtering role on solar radiation and interacted with the PCM to reduce heat losses.…”