In addition to the standard commissioning requirements for certification available here, the following advice from WARM’s experience is helpful in achieving a ventilation system that will comply and work well. We’ve split this up into the ventilation system, unit and BMS commissioning but the split may be different for specific projects. It is the team’s responsibility to ensure all these things are achieved.

Before you start

1. Confirm how the units are controlled. Key ambition is to achieve air in = air out (equalised) for each ventilation unit over the range of setpoints.

To set the airflow in and out.

1a)For some units airflow is measured within the unit. Get confirmation from the certifier it's sufficiently accurate. E.g. Swegon Gold, Menerga or Zehnder Comfortair. In this case we would expect equalisation is set by the ventilation unit – typically called master and slave – see below.

1b) For other units it's simply a voltage input. In this case expect supply & extract to be equalised by the ventilation commissioning engineer. e.g. Nuaire and Airflow Fexi. See below:

2. CHECK the design, does each unit have equal supply and extract air? Units might be set to run at different time schedules so the systems need to be equal at each unit across all airflows, rather than across the building.

3. If the system is variable flow:

3a) If airflow is measured within the unit it should be possible to slave supply off the extract, to constantly equalis

3b) If it's a voltage input the equalisation of supply and extract can change over the range of airflows. Ask the designer to confirm the flowrates per unit for 'typical' conditions. It is recommended to equalise flowrates at this typical flowrate rather than the maximum.

During the ventilation commissioning

1. Determine the most accurate way of measuring the flow in and out of each ventilation unit, agree method with the Passivhaus designer and see notes above. The supply must equal the extract with an absolute maximum disbalance of 10%.

If unit is 1b type, confirm what flowrate is set to equalise the system and equalise by measurement of (in order of preference)

1i) Consider measuring intake & exhaust terminals (balometer)

1ii) Pitot tube traverse on main ducts from unit

1iii) Or sum supply and extract terminals (balometer).

2. Commission the terminals to the flowrates required on the drawings.

3. Check the total flowrate from either i or ii above match the sum of the terminals, if there is a significant error this may be due to a defect within the system. If this is the case consult the certifier.

4.Aim for total supply and total extract +/- 5% of design figures. Note greater airflow means greater heat loss so hence keep close to design.

5. Confirm what equipment was used & mark where measurements were taken from on drawings.

6. Measure/read off from unit the static pressure for both the supply and extract legs, record flowrate.

7. Measure/read off from unit the specific fan power, record flowrate.

8. Measure noise levels if it has not been calculated during design - check with your designer for further advice on this.

Evidence provided: this should be presented as a commissioning report and in excel format for easy input to PHPP.

During the unit setup/commissioning

1. Confirmation of settings for control of heat recovery. In most situations this is most effective if based on achieving a return air temperature.

2. If '1a' type control, confirm set up to keep flowrate equalised – recommendation is to slave extract off supply. Evidence that at key duty points the system is in balance.

3. If it is '1b' type and variable air flow, provide proof of performance against sensors and identify voltage input.

4. Readings of static pressure/total power at duty points for comparison against design assumptions & power consumption (if not gathered by commissioning engineer)

5. Confirmation that filters are F7 (intake) and G4 (extract) and are clean.

6. Confirmation of any controls or sensors connected directly to the AHU and setpoints.

7. Confirm how the AHU is set up to keep flowrate equalised – recommendation is to slave extract off supply for all flowrates.

Evidence provided: screenshots of the various controls, photos of all other aspects

During Building Management System commissioning

1. Provide evidence of any time schedules or other sensors and controls of the vent systems. this might be more significant for specialist systems such as the kitchen ventilation where keeping the unit in balance may be done through the bms, see notes above.

2. If the BMS controls any of the items highlighted in the ventilation unit or commissioning sections make sure that these are adequately completed.

3. Check controls to turn dampers off when unit is turned off.

Evidence provided: screenshots of the various controls, photos of all other aspects.