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Community and Q&A

The UK requires trickle vents now? Wdyt?

jonathanb | Posted in Energy Efficiency and Durability on

I recently learned about trickle vents. Apparently as of June 15, 2022 they’re now a requirement in the Building Regulations of England:

Back in 2016, people on this site were recommending against the idea:

Has anything changed? Have air tightness standards gotten stringent enough? Why would the UKĀ  recommend passive trickle vents instead of HRV/ERVs?


  1. Expert Member
    PETER G ENGLE PE | | #1

    Based on a quick reading of the referenced document, here's my take. Note that I do not claim any particular expertise in UK building codes and standards.

    The UK codes require three different types of ventilation: Extraction Ventilation (for kitchens, baths, utility rooms, etc.) "Background Ventilation" to provide constant fresh air to the occupants, and Purge ventilation for removing intense odors or other indoor pollutants. Trickle vents are mentioned in the first two, but primarily to meet the Background Ventilation requirement. You can meet this requirement for Background Ventilation using just trickle vents, using an exhaust-only fan system with trickle vents for Make-Up Air (MUA), or using an HRV/ERV system. Note that any ventilation system must also meet UK's energy standards, so anything but an HRV/ERV system may be problematic.

    This really isn't any different than the US codes. Our codes allow the equivalent of Trickle Vents as MUA for combustion appliances, among other things. Trickle vents are not "required" by the UK codes but they are allowed as one way to meet the background ventilation requirements of the code, so long as the overall building meets the other requirements of the codes including the energy efficiency requirements. Nothing in the UK changes the findings from American labs that trickle ventilation doesn't work. The physics remains the same. But few people, either in the UK or the USA would accuse their code-making bodies of being even marginally aware of either physics or recent real-world test results. Dumb things get rolled into the codes all the time.

  2. jonathanb | | #2

    That would make sense! Trickle vents are allowed, but not required. ERV/HRV systems are the more energy efficient way to meet the requirements.

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