Page 23 - ZEB Final Report 2009-2017

Hot or Cool? | 23

Maria Justo Alonso Laurent Georges
Researcher, SINTEF Associate Professor, NTNU

Heating and cooling are challenges in super insulated buildings.

The answer might be a ventilative cooling system.

Is heating and cooling of residential ZEBs buildings without increasing energy ZEB Living Lab where periods of too
and traditional buildings different? ZEB demands during summer and milder high temperatures have been removed.
has worked on answering this question. periods. Essentially, the air is driven In addition, users who are able to control
ZEBs have high energy efficiency by natural ventilation (typically using their thermal environment by opening
basically promoted by a super-insulated, controlled window opening). Research windows tolerate higher temperatures.
airtight envelope, equipped with in ZEBs has proved the efficiency of A similar study has been carried out
balanced mechanical ventilation with ventilative cooling, for instance in the in non-residential ZEBs.
heat recovery. Such buildings pose new
challenges and opportunities for heating
and cooling systems.
Firstly, super-insulation enables a
reduction in the number of heaters, such
as radiators, inside the building, which,
in turn, reduces the cost of the heating
system. Simulations, field measurements
and interviews show that occupants are
satisfied with thermal comfort using
simplified distribution. One might
suppose that removing heaters from
bedrooms would make them too cold. On
the contrary, research shows that many
occupants still experience these rooms as
too warm. Secondly, research shows that
the design procedure should be adapted
to super-insulation. There is a risk that FIGURE 1. Measurement of indoor temperatures in a passive row house with simpliied space
the power of the space heating system heating: the temperature of the large bedroom is reduced by opening windows frequently
may be over dimensioned, which can while the temperature of the neighbouring small bedroom is kept relatively high.
negatively affect both cost-effectiveness
and the operation of the system. The
need for domestic hot water (DHW) takes
precedence over space-heating needs,
therefore systems should be optimized
for the DHW demand.
The risk of overheating in summer
may be greater in super-insulated
buildings. Nonetheless, the potential of
ventilative cooling in Nordic countries is
high and can prevent overheating without
the need for mechanical cooling (such
as chillers). With ventilative cooling,
large quantities of outside air cool the FIGURE 2. Principles of hybrid ventilation in the Living Lab to achieve ventilative cooling.