form factor and passivhaus

September 23, 2014

HH front render

It is well known that compactness is an important aspect of a well designed and cost effective Passivhaus as it has a considerable impact on the overall heat demand.  Having now modeled a number of projects in PHPP (Passive House Planning Package), I decided to do a quick comparison of the ratio of envelope to floor area (known as the form factor) as well as the average R-value of the entire envelope.  Here are a few examples:

Emerson

envelope to treated floor area:  3.8

average R-value:  39.4

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Skidmore

envelope to treated floor area:  3.7

average R-value:  29.7

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18th Ave Residence

envelope to treated floor area: 3.2

average R-value:  24.1

_

Haig Haus

envelope to treated floor area:  2.7

average R-value:  25.9

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Ankeny Apts

envelope to treated floor area:  1.5

average R-value:  19.7

 

While there are many variables at play that make each project distinct, it is clear that form factor has a huge impact.  Remember boxy can be beautiful!

 

 

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