3.1. Zero energy buildings
Some of the first documented attempts towards zero energy
were in reality an attempt to achieve zero-heating in the form of
solar houses. Early examples include the 1939 MIT Solar House I,
which included a large solar thermal collection area and water
storage [30], or the 1955 ‘Bliss House’ [31] using solar air collectors
and rock mass storage. Examples from the 1970s include the Vagn
Korsgaard Zero Energy Home in Denmark [32] or the Saskatchewan
Conservation House [33]. These were also designed for zero
or near zero heating incorporating higher insulated envelopes. The
Saskatchewan Conservation House used some features that are
now becoming mainstream in passive and low-energy construction
such as good air tightness (1.3 air changes at 50 Pa) and air-toair
heat exchangers. This approach allowed a reduction in the area
of solar collection surface and solar storage when compared to
previous zero-heating installations.
These early examples have been influential in current
approaches to building design and indeed contributed to the
definition and upgrade of building standards and regulatory codes.
Voluntary standards for low-energy buildings using the principles
of high insulation, good air tightness and heat recovery ventilation
systems are increasingly popular, such as the scheme R-2000 in
Canada [34] or the Passivhaus in Germany [35], and are now
extending to other parts of the world. While those standards are
not zero energy nor zero-heating they do achieve reductions in
heating energy demand using a practical and cost-efficient
approach, which most experts would consider a good first step
towards zero energy building (ZEB). These solutions also generally
use lower quantities of material than more extreme zero energy
solutions. If analyzed from a life cycle energy perspective such