Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 354

has the advantage of simplicity, but prevents some controllability -
particularly if different temperatures are desired in different spaces or if
heat gains (e.g., equipment or solar) are unbalanced.
Care of thermostat placement must be taken in passive solar houses. For
instance, if it is placed in the direct solar gain zone, there is a risk that
that space will overheat and the thermostat will send the control signal to
turn off the heating supply - even if other parts of the house are too cold.
The ÉcoTerra house has two means to mitigate this risk: (1) it is an open
concept, so natural air circulation helps distribute solar gains and (2) the
high-efficiency air distribution fan can be activated in circulation mode,
such that air is circulated within the house even with no heating or cooling.
A heat recovery ventilator (HRV) was installed to recover sensible heat
from the exhaust air. The selected model has a sensible effectiveness of
72%, consumes 95 W and exchanges air at 70 l/s at high speed mode.
While it was initially configured to always operate in high speed mode,
this was later modified such that it remains in low speed mode (34 W of
power consumption) unless the bathroom or kitchen fans are activated. An
air-cleaner is connected in series with the HRV; however, it is somewhat
redundant to the HRV since the HRV also has an air filter.
The domestic hot water (DHW) heating is achieved in one of three ways: (i)
preheating by the BIPV/T air, (ii) desuperheater from the GSHP, or (iii) by
an auxiliary electric heater. The system has both a preheat and regular tank
- both with a volumetric capacity of 240 l.
The installed major appliances are primarily low-energy and EnergyStar
rated. They are all electric, including a refrigerator, oven/stove, and clothes
washer and dryer. While the installed lamps were mainly compact
fluorescent, the owners installed approximately 24 halogen lamps after they
moved in (discussed later).
7.2.2 Design Process
Thissectionprovidesabriefsummaryofthedesignprocessthatwasapplied
to ÉcoTerra in 2006. Its main purpose is to document the process so that
it can be used as a model; meanwhile, the effectiveness of the process is
discussed.