How accurate is building energy modeling software? There are a lot of assumptions that go into any model. We assume that the weather will conform to historical climate data, that occupants will use the building in a typical manner, that the building is actually constructed as designed, that mechanical equipment will perform as advertised, etc. The chart above shows measured data—blue bars—plotted against the simulation results for Passive House and low-energy buildings in Germany. This shows how well the Passive House Planning Package (PHPP) software can predict average energy use. PHPP has been validated with dynamic energy simulation tools as well as with measured data. You can read the US Department of Energy evaluation of PHPP here.
PHPP version 9, which is slated for release towards the middle or end of 2014, will feature two additional worksheets entitled Variants and Comparison along with other innovations. The Variants sheet gives users the option of inputting different designs and displaying the results in parallel. The Compare sheet allows two of these variants to be selected to compare their energy demand and affordability in depth. [Passipedia]
Another tool, the PHeco external calculation tool (not integrated into the PHPP) has been developed by the working group for cost-efficient Passive Houses [AKKP42 2012]. This worksheet uses the PHPP’s findings to calculate affordability. It does so by comparing different building designs’ heating energy demand and the costs of their respective energy-saving measures. The PHI can provide this tool on request. [Passipedia]
Duncan Architect consults with architects, engineers, and contractors to provide energy modeling services, among others. As a Certified Passive House Designer, Gregory Duncan is well qualified to create accurate energy models using PHPP software.
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