Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 159

into additional lighting and cooling energy costs - or additional design and
time costs to redesign - at the later design stages.
Internal gains generated by plug loads and electric lighting have an
important impact on space heating and cooling energy requirements. In the
concept design phase, typical power densities for electrical equipment and
lighting should be introduced in the model according to the building type.
The concept for the building-integrated solar energy technologies should
be an integral part of the early stage Net ZEB design. Aside from solar
energy systems' impact on the building's net energy balance, they have
inherent effects on many of the building's other aspects, such as form,
program, envelope composition, and structure. For instance, the ÉcoTerra
house's roof shape was largely dictated by the dimensions of the preferred
photovoltaic modules (more details in Chapter 7 ).
Even though no detailed work is done regarding HVAC at this stage, the
future integration of HVAC must still be considered in the design process.
The general concepts for this aspect might have already been discussed in
the preparation phase.
Operating strategies and some comfort parameters need to be considered
at this stage. If radiant floor heating is to be used, then the thermal mass
integrated in the floor should be considered both for storage of passive
gains and auxiliary heat as well as an appropriate control strategy should
be established. Operating strategies also need to account for the expected
occupancy profile of the building. For example, night cooling using cool
outdoorairisabetterstrategyinofficebuildings,whereoccupantsnormally
leave the building at night, than in homes where it could cause discomfort.
Thus, the zone temperature setpoints and their allowable fluctuation need
to be decided.
4.2.4.1 Daylight
A building with a well-insulated envelope may have high energy
consumption if the architectural concept does not allow for natural light
to penetrate into the building, especially for office buildings. Natural light
is more a geometrical problem than a technical problem and typically, the
potential for natural lighting is better in a long and narrow building than
in one that is deep and compact. An atrium is an example of a strategy
that can be used to provide natural lighting in a compact building. Figure
4.1 presents an example of a commercial building with an atrium at the