INFLUENCE OF GEOMETRY ON ENERGY EFFICIENT DESIGN


Building size and aspect ratio


The building dimensions are one of the most important factors to consider when designing to minimise the CO2 emissions of a building.


Excessive floor area, height and volume will increase energy consumption, so an oversized building should be avoided. Even if expansion is expected, it is worth thinking about using a smaller building that can be extended, or bringing nearby buildings into consideration.


Design for use of building floor area


Our in-depth studies have found that decreasing the height of the eaves reduces the CO2 emissions of a building. This is largely due to the reduction in energy required to heat the building, as there is a smaller volume of air to heat per m2


from this work is that energy efficient buildings should not be designed any higher than necessary, in relation to what they will be used for.


Design for use of building volume


The main factor when designing the most efficient use of a building’s volume is the surface area to volume ratio. Where efficient use can be made of the height and volume (for example, by using modern racking systems), a taller building will cut total CO2 emissions.


Figure 2. Effects of shape and size Case Size (L x B x H)


Small low 60m x 30m x 6m Small high 60m x 30m x 10m Medium 120m x 60m x 10m Large


Kg CO2/m2 31.7


240m x 120m x 17m


36.2 36.1 45.5


Floor area


/yr Change from base Kg CO2/m3 -12.0%


+0.4% Base


+26.1%


4.9 3.4 3.5 2.6


/yr Change from base +41.3% -0.2% Base


-24.7% Volume


These recommendations need to be balanced against possible future changes of a building’s occupier and the building being used for a different purpose.


of floor area. The main conclusion


55


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