Civil Engineering Reference
In-Depth Information
Fig. 16 G-value versus U-
value for different net heat
flux during the heating season
(approximately October-
April) for a single-family
house in a Danish climate.
The star represents a glazing
with 15-mm monolithic
aerogel. The dots mark the
values for conventional
glazing units (Schultz et al.
2005
)
0.5 W/m
2
K and a g-value equal to 0.75 was considered, and the results were
compared to a triple-layered argon-filled glazing with two low-e coatings
(U = 0.6 W/m
2
K and g = 0.46). The annual energy saving with aerogel glazing
was approximately 1200 kWh/year, corresponding to 19 % of the energy for triple
glazing (space heating demand equal to 5,040 kWh/year for aerogel, 6220 for
triple glazing). In a low-energy house (space heating demand \ 15 kWh/m
2
/year),
the energy savings was approximately 700 kWh/year, corresponding to 34 % of
annual space heating demand (about 2,070 kWh/year).
Nevertheless, in southern climates, the increase in cooling needs, due to the higher
solar factor, diminishes the advantage of aerogel glazing, and in some cases, a higher
global energy consumption during the year could be obtained (see
Sect. 5.2
).
Finally, a comparison between the indoor visual comfort with aerogel windows
and conventional glazing systems was simulated by means of the calculation code
RADIANCE in an office room. Results showed a better diffusion of the direct light
for aerogel glazings, with respect to a conventional double heat-reflective glazing
(with low-e film), reducing also glare (Fig.
17
). The worst situation for aerogels is
the one with direct sunlight on the surface (Fig.
17
b).
5 Building Refurbishment with Nanogel Windows
An experimental application of granular aerogel windows is presented in
Sect. 5.1
,
and the benefits are evaluated in terms of light transmission and energy saving
(heat loss reduction).
A multifunctional building was then investigated in
Sect. 5.2
, and a dynamic
thermal model was implemented. The energy demand was estimated for different
