MVHR commissioning in Certified Passive House Buildings (includes PHI Low Energy Building Standard and EnerPHit as well)

28 March 2019 by Jason Quinn

In order to certify your building as meeting the exacting Passive House Standard the certification standard “Criteria for the Passive House, EnerPHit and PHI Low Energy Building Standard, version 9f, revised 15.08.2016” requires in 3.2.5 Ventilation:

HRV commissioning report: at minimum, the report must include the following: description of the property, location/address of the building, name and address of the tester, time of adjustment, ventilation system manufacturer and type of device, adjusted volume flow rates for standard operation, mass flow/volumetric flow balance for outdoor air and exhaust air (maximum imbalance of 10 %). A report should be provided regarding the adjustment of all supply air and extract air valves. If this is not possible in individual non-residential buildings for technical reasons, then at least the volume flow rates in the ventilation unit (outdoor air/exhaust air) and in the principal ducts of the ventilation system should be measured. Recommended: “Final Protocol Worksheet for Ventilation Systems”, source PHPP CD or

To summarize there are three reasons and technical bits to commissioning the ventilation system in a single family detached Passive House:

  1. Overall in/out balanced ventilation at Standard or Average flow rate from PHPP where the dis-balance is less than 10% (i.e. supply/exhaust are within 10% of each other) – this is done by either:
    1. Using built in accurate flow sensors in the MVHR if the MVHR company has provided data sheets showing the air flow measurement accuracy. This could allow this portion of the commissioning to be done remotely for single family detached homes.
    1. Measuring each inlet/outlet using balometer or powered flow hood then adding up to arrive at total.
    1. Measuring the actual inlet/outlet outside the building again using a balometer or powered flow hood or in this case a vane anemometer. I’d accept a vane anemometer as it is typically less accurate but as it is one big measurement it should be sufficiently accurate.
  2. Room-to-room splitting out the supply/exhaust measurement. This is less important to be exactly accurate but the proportion is important so that we know you have enough fresh air in the bedrooms for restful sleep and the health benefits that brings. In bigger buildings/projects I’d expect a proper balometer or powered flow hood to be used but for single family detached I believe a vane anemometer is sufficiently accurate to ensure the split is correct. One additional point is the testing should be at the typical setting and the door to rooms must be closed. This will tell us if the undercut or overpass for return airflow is sufficient. This is super important that the bedroom should be closed if you sleep with it closed.
  • Acoustics. Requirement in the Final_protocol_worksheet_manual.pdf of 25 dB(A). This is really hard to measure – as in stupidly hard. Best approach is to use the calculator in the PeterWarm tool from Sally’s presentation available from see  Ventilation Commissioning Guidance and Design/Commissioning file.   Best to walk through each room and measure 1.5m below the outlet then turn off the MVHR and repeat. The calculator on the second sheet looks to estimate the MVHR noise without any other noise. Essentially you shouldn’t be able to hear the MVHR in the bedrooms at all.  As an alternate I’ll accept the owner/occupants statement that the MVHR is not audible at the normal setting even when the house is quiet.

Note: I use Decibel X Pro ($4 USD) on my Samsung S7 and it matches a calibrated sound meter fairly well over the 25dB(A) to 70dB(A) range. Well enough to not require the use of another piece of kit.

The amount of air per room (room-to-room split) must be supplied to the person doing the ventilation commissioning as a worksheet partially filled out. I’m fine with either the ‘Final_Protocol_Worksheets_Ventilation.xls’  from PHI  or ‘Final_Protocol_Worksheets_WARM_v121.xls’ from Peter Warm’s website. The amounts need to sum to the typical flow in the PHPP from step 1 above. I will no longer issue pre-construction letters to clients without this form completed.


Directions from PHI are:

Materials / files are available at:

For your reference on your PHPP (Passive House Planning Package) CD there is a folder called Tools

In this folder is a blank template for the Ventilation System Commissioning called ‘Final_Protocol_Worksheets_Ventilation.xls’ and some brief directions ‘Final_protocol_worksheet_manual.pdf’

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