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9 ZEB annual report 2014
to be the one that minimizes, on an annual
basis, the sum of the primary energy demand
for heating, cooling and lighting. The results
indicate that although there is an optimal
WWR in each climate and orientation, most
of the ideal values can be found in a relatively
narrow range (0.30 < WWR < 0.45). Only
south-oriented façades in very cold or very
warm climates require WWR values outside
this range.
Optimal energy supply and building services
systems are also important. The substantial
reduction of heating load in low-energy and
passive house buildings has led to simplified
heating systems. It is suggested that air
heating should be supplemented by an extra
heat source in bathrooms, and it should be
possible to adjust the supply-air temperatures
in the bedrooms separately from those in the
other rooms. These findings are supported
by questionnaires among people living in
Norwegian passive houses. Furthermore,
nominal power of state-of-the-art wood stoves
was oversized for the needs of highly-
insulated buildings. A model was developed
to investigate the indoor thermal environment
generated by wood stoves. A specific
experimental setup has been developed
to validate this modelling procedure. It
was demonstrated that the model makes
it possible to investigate how to accurately
dimension a wood stove.
The zero emission building concept requires
a new way of thinking of the energy system,
as the energy flows are no longer only flowing
from central energy producers to small end
consumers. Therefore, we have studied how
the power market and the power system will
be influenced by large scale introduction of
zero emission buildings. A dynamic model with
hourly time resolution has been developed,
and it showed that the optimal investment
decision was a combination of a bio pellets
boiler, a photovoltaic system, and an electric
boiler for peak load.
New materials have also been developed.
Nano insulation materials (NIM) consisting
of hollow silica nanospheres (HSNS) have
been synthesized and we have succeeded in
making hydrophobic HSNS without increasing
the thermal conductivity. Furthermore,
a method for the integration of life cycle
assessment (LCA) in the design of NIM as
HSNS has been developed. This method may
also be utilized in the design and development
of other new materials. The thermal resistance
of concrete has been considerably increased
by incorporating aerogel. However, to increase
the thermal resistance more than the decrease
in the mechanical strength represents a
large challenge. New aerogel glass materials
have been successfully prepared with a low
thermal conductivity (k ≈ 0.17 – 0.18 W/(mK)),
a high visible transparency (Tvis ≈ 91 – 96%
at 500 nm) and a low mass density (ρ ≈ 1.60
– 1.79 g/cm3). Thermally insulating aerogel
glazing units (AGU) have been assembled
by incorporating silica aerogel granules into
the cavity of double glazing units, which
demonstrated that solar radiation (e.g. Tvis and
Tsol) and thermal properties (e.g. U-value) are
very dependent on the granulate size.
Last, but not least, in 2014 four ZEB PhD
candidates defended their theses. These
were;
• Liana Müller; “From Law to Turnkey:
Negotiating Sustainability in Buildings”
• Usman I. Dar ; “Influence of occupants’
behavior on the performance of Net-Zero
Emission Buildings”
• Krishna Bharathi; “Sustainability in
Practice: Social Science Perspectives on
Architectural Design, Research and the
Implementation of Buildings Solutions”
• Nicola Lolli; “Life cycle analyses of
CO2 emissions of alternative retrofitting
measures”