How to scale HRV data to ERV for use in Passive House PlanningPackage

Summary

Several Heat Recovery Ventilation (HRV) systems available have HRV performance data for the Passive House Planning Package (PHPP) but do not have Energy Recovery Ventilation (ERV) performance data. Knowing the performance is important for designing Passive Houses. A simple scaling is suggested to provide a first approximation.

Method

Looking at the PHPP version 9.3 example file we can set a ComfoAir350 HRV (and put in inside the thermal envelope as is typical)

ComfoAir 350 data entered into PHPP. Efficiency results.

ComfoAir 350 data entered into PHPP. Efficiency results.

Now what if we want to use a ComfoAir350 ERV we don’t have that option built into PHPP as there is no certified ComfoAir350 ERV even though that core is available.

Looking at the other options we can find that the ComfoAir 160 has both a HRV and ERV option certified:

ComfoAir 160 has both ERV and HRV data that can be used to scale other ComfoAir units performance.

ComfoAir 160 has both ERV and HRV data that can be used to scale other ComfoAir units performance.

Switching back and forth we can see that changing the example in Germany we would have 3% higher SSHD and 1% higher heating demand by changing from a HRV to an ERV.

Without testing data from the manufacturer the reasonable course is to scale the ComfoAir350 properties. This is reasonable as the same unit is used with only the core being swapped out, the ComfoAir 350 and 160 use similar heat/energy exchange technology with the main difference in efficiencies due to the higher surface area/flow in the ComfoAir160.

I’d recommend scaling the HRV down by 0.84-0.04/0.89 the ERV recovery to 0.64*(1-0.04/0.89) and conservatively leave the power usage the same. Scaling in this manner results in a slightly more conservative reduction in performance for the PHPP Example provided by the Passive House Institute (PHI). For certification to the PHI standard test data or a slightly more conservative number would be required.

Scaled data entered into PHPP.

Scaled data entered into PHPP.

Reference: PHPP Manual version 9 by Passive House Institute, Darmstadt, Germany.

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