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hand, a double-glazing with aerogel filling
with a similar U-value has a g-value of 0,75,
which means a window with the same thermal
insulation property and higher transparency.
This is very favourable, as a high g-value
allows for high solar radiation, which in winter
is beneficial for reducing the energy required
for space heating.
However, it must be noted that depending
on the form of the final product (powder or
monolith), the optical properties of aerogel
varies. While monolithic aerogel shows a
visible transmittance which is comparable to
glass, granular aerogel shows much lower
values of visible transmittance, as the material
is translucent. In such a perspective, the use
of granular aerogel in residential buildings
may have a limited application due to its
translucent appearance.
The energy simulations showed that the
substitution of triple-glazing with argon gas
with aerogel glazing (either monolithic or
granular) saves up to 20% of the delivered
energy for space heating. This is due, as
explained above, to the high solar radiation
through aerogel windows.
The calculation of the lifecycle of greenhouse
gas emissions showed that the building
lifecycle emissions decrease by 9% when
the aerogel windows substitute triple-glazed
windows. In figure 3, the comparison
between the use of either aerogel windows
or triple-glazed windows represents the
most significant results (space heating, total
building energy use, and building lifecycle
emissions). The values are obtained by
dividing each result given by the use of
aerogel windows by the same result given by
the use of triple-glazed windows. In the first
column the different windows types (granular
aerogel, monolithic aerogel, and triple-glazing)
and the different glazing ratios (amount of
glazed area/total facade area) are shown. It
is possible to conclude, from the results of
this study, that the use of aerogel windows
is beneficial for the reduction of the building
energy need for indoor space heating and the
lifecycle emissions for a residential building
located in Norway.
For å få bukt med den lave termiske
motstanden i transparente overflater er det
utviklet vindustyper med flere lag glass,
hvorav et bredt utvalg er tilgjengelig i dagens
marked. Trelags vinduer med lavenergibelegg
og argongassfylling er eksempel på en effektiv
energispareløsning. Disse teknologiene har
imidlertid den ulempen at de, som følge av de
mange lagene med belegg, drastisk reduserer
andelen solstråling som trenger gjennom
glasset. Dette kan være ugunstig på nordlige
breddegrader (som i de skandinaviske
landene) der solstrålingen i vinterhalvåret er
liten både med tanke på tilgjengelighet og
lyskvalitet. Glass med aerogelˆ er fremmet
som en teknologi med evne til både å
slippe inn mer dagslys og med en bedre
isolasjonsverdi enn tradisjonelle vinduer med
tre- og firelags glass. Resultatene presentert
her sammenligner og vurderer utslippene av
drivhusgasser (GHG) fra tre ulike teknologier
benyttet ved renovering av et boligkompleks
Figure 1. Top left and centre: the West and East façades of the test building, the Myhrerenga Borettslag before renovation. Top right: the original drawing of the
cross section of one the apartment buildings. From Lolli, N., Life cycle analyses of CO2 emissions of alternative retrofitting measures, Ph.D. Thesis, Norwegian
University of Science and Technology, 2014.