Post-Occupancy Evaluation (POE)

Posted by on Aug 13, 2014 in Post-Occupancy Evaluation | Comments Off on Post-Occupancy Evaluation (POE)

Post-Occupancy Evaluation (POE)

We are interested in how Passivhaus buildings actually perform and we thought you might be, too.

We want to understand how occupants are finding living in low-energy homes and whether their Passivhaus homes are living up to their (and our) expectations.

The following graphs present the first stages of our analysis.  They cover a number of certified Passivhaus dwellings that we have had involvement in over the last couple of years.

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Carbon Emissions

CO2 emissions take account of all energy used by the household. Standard national conversion factors are applied to the different fuels used by the building occupants, and these factors also take account of energy consumed/lost in generation and transportation.  As carbon emissions consider all energy used by the occupants, and not just the energy that can be influenced by the building design, the final value depends a lot on occupant lifestyle, which is reflected in the data below.

We have plotted an equivalent value for the “primary energy” upper limit, which is what the building was designed to use.  As well as this, we’ve plotted the UK 1990 average, the 2012 average (which is interesting because of the increase), and the Government’s 2050 target, which is 80% of the 1990 level.

The Passivhaus primary energy limit is pretty close to the 2050 target, although further work would be required (e.g.  in appliances and lighting) to achieve the target consistently.

The design primary energy limit of ~18 kg/m2 of CO2 compares fairly well with the average of our houses at 21 kg/m2 of CO2.


Heating Energy

We wondered what the performance gap was between the heating energy predicted in each PHPP and the reality, and how this compares to some other well-known targets.  Nearly all the buildings perform better than the PHPP prediction.

Generally, the average internal temperature is comparable to the PHPP prediction of 20oC, but there are some oddities; house 12, for example, is using a lot of energy, but is on average fairly cool. Further investigation is needed to understand what’s happening here. It may be a building fault, or just that the windows are being left open.

Note that most of these figures relate to heating season 2013-14, apart from house 23, which was 2011-12.  The data has not yet been corrected for the variation in weather.


If you’ve got a project you’ve got data for and you’d like us to include it in this analysis, please email carolineemail.