Design fundamentals - The Hempcrete Topic: Designing and Building with Hemp-lime - page 522

obvious changes in behaviour such as wearing a coat in colder weather. The most reaction
many people ever have to the weather is to move the dial on the heating control.
Even if moisture ingress is not (theoretically at least) an issue in modern conventional ma-
sonry buildings, the lack of thought about the prevailing weather on-site during the design
of new builds leads to high levels of inefficiency in power use as a result of poorly sited
buildings. All of us will be able to think of times when we have sat in a home or workplace
that was overexposed to driving wind in the winter, making it too cold, or to direct sunlight
in the summer, causing overheating. As well as incurring increased insulation costs, such
buildings often need to be fitted with higher-powered air-conditioning or heating systems,
which have a direct impact on the running costs and environmental impact of the building.
In the last 60 years or so, such inefficiency was not a critical factor in design, but as we
move forward into a world where energy resources are increasingly scarce and costly, such
inefficiencies need to be designed out of all new buildings.
Furthermore, it is important to remember the vulnerability of all materials, including
hempcrete, to excessive moisture ingress (as discussed on page 293 ) , and the tendency
of all walls to exhibit reduced thermal performance when moisture content gets too high.
With these factors in mind, it is clear that to use any natural building material to best ef-
fect, thought needs to be given to how the topography and climate of the proposed site is
likely to affect the performance of the materials. Simple changes to the siting and orient-
ation of the building, the landscaping of the site, or the detailing of the building itself at
the design stage can mitigate less-than-ideal conditions. With a little care it is possible to
create a building that truly maximizes the potential of the natural materials, with potential
problems designed out.
Much has been written elsewhere on this topic, and it is not our intention to replicate it
here, but a few of the key issues, as applied to hempcrete, are outlined below as examples
of things the designer should be keeping in mind.
Site-specific solutions
There is unlikely to be a 'one size fits all' solution when detailing hempcrete. First, con-
sider the conditions and topography of the specific site and outline the challenges they
bring through differing levels of exposure to prevailing winds, rain and sun. Consider the
position of the sun at different times of the year - high in the sky in summer; low in winter.
Is it possible to design in, through the siting and orientation of the building or through
features such as windows and skylights, shade for the interior from the high, hot summer