18 December 2020

“An insulation project without ventilation is a condensation project”

A recent post from David Pierpoint of the Retrofit Academy on social media highlighted the importance of ventilation. He shared this quote from one of his tutors and it has been lodged firmly in my mind ever since:

An insulation project without ventilation is a condensation project”

The message is simple and stark, but ventilation has not been at the forefront of our thinking in domestic retrofit … until now.

What is ventilation anyway?

It may sound like an odd question, but ventilation can mean different things to different people. For some it conjures up the image of an extractor fan whirring away in a bathroom, for others an open door or window on a hot day.

Both are forms of ventilation, that are equally important to control the input of fresh air and ensure moist stale air is expelled from the building.

But why is this important? Quite simply for:

  • A healthier home – prevent the build-up of moisture on surfaces and in structures
  • Healthier occupants – a damp environment with stale contaminated air is not a suitable environment
  • Our general safety – where combustion appliances require an input of air into a room to ensure that they operate in a safe manner.

Why the focus now? 

Our insulation techniques are certainly getting better.  We are increasing the air tightness in our old leaky homes and reducing draughts to improve comfort and prevent heat loss, saving energy in the process. Our windows and doors are better sealed, and our lofts and cavities are often well insulated.

At the same time, our homes have traditionally been ventilated in an uncontrolled manner, with the provision of trickle vents in windows and the odd air brick (which may have not been sealed up during re-decoration) supplementing the gaps in floorboards, skirting and other air leakage paths.

When we insulate a building correctly, particularly as we move towards whole house retrofit, we close off these air leakage paths, which is positive from an energy efficiency perspective but potentially destructive if moist warm air has no escape. This can increase the risks of condensation, damp and mould growth.

It may sound counterintuitive, but when we insulate and effectively ‘seal up’ the fabric of a building, we must ensure that there is sufficient provision of air inlets for fresh, dry air and air outlets for stale, moist air. Ventilation requirements are not widely understood across the supply chain, but they are now set out in Annex C of PAS2035 and the requirements are well-defined compared to the less prescriptive PAS2030:2017 standard. The message is clear; if the ventilation is inadequate, you must bring it up to standard whilst installing a new fabric insulation measure.

The Green Homes Grant Voucher Scheme offers an opportunity to ramp up capacity in the supply chain to allow us to step-change the scale of our efforts to better insulate our homes. Whilst a mandatory Retrofit Assessment (including a ventilation assessment) would have been the ideal accompaniment, I understand why Government has landed on a hybrid approach to mandating PAS2035 and PAS 2030:2019 approaches for riskier measures only. The question is:

Will a rapidly expanding supply chain adopt the correct approach in relation to ventilation in time?

Now I’m no fortune teller, but I’ve forecasted a few fairly significant issues in delivery over the past few years and what I do foresee is a challenge in relation to the adoption of good ventilation principles.

Our advice would be to:

  • Assess the existing ventilation thoroughly
  • Understand the requirements for that home
  • Carefully plan any necessary upgrades and cost them into your work
  • Make sure you manage the customer expectation, particularly when new core vents may need to be drilled in existing walls which may be decorated or tiled
  • Make sure your team understand why ventilation is so important

Finally, don’t be afraid to ask for help.  For more information and to find out more about how our pre-installation check services through RETROFITcheck can support you, don’t hesitate to give us a call.

Merry Christmas and Healthy New Year to all.

Adrian Hull is a Qualified Retrofit Coordinator and MD of THS.

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