Clarissa Youden, associate director of Total Home Environment discusses how you can reduce building maintenance and fuel poverty, while offering dramatic health benefits
So you’ve got old housing stock, with complaints of mould, condensation and high heating bills. While a bit of remedial work – insulating the loft and filling cavity walls – has done a little to alleviate things, nothing’s really changed. Residents are still grumbling, falling back on payments as they prioritise heat over rent. And what’s worse, there’s even more remedial decoration work than there was before. So why is this happening?
Firstly, the properties are probably still incredibly leaky, with thermal bridging going on all over the place. Even with small five millimetre gaps in insulation, significant heat loss will still occur and you might as well have not bothered. Secondly, the windows are single or if you’re lucky double glazed, but because the last refurb was 30 years ago, they’re probably failing. Furthermore, it’s likely some of the trickle vents have been shut by residents as many people find them too draughty, but they’ll still run appliances like the tumble dryer. Extractor fans also help deal with condensation, but when was the last time they were cleared of dust, let alone replaced? This lack of adequate ventilation is causing excess condensation, mould growth and awful indoor air quality.
The solution is to make the properties completely airtight, insulate them up to the hilt, put triple glazing in and provide complete whole home heat recovery ventilation to keep the air inside clean and healthy. This approach is termed as the EnerPhit Standard – the PassivHaus strategy for retrofit properties which leads to considerable improvement in thermal comfort, structural protection, cost-effectiveness and energy efficiency.
What is heat recovery ventilation (HRV)?
Whole house ventilation is completely controlled to provide the correct amount of fresh air, when it’s needed and with great heat recovery. A fan unit located remotely continuously extracts stale air out of wet rooms, while drawing fresh filtered air from outside. They pass each other in a heat exchanger (not mixing) and up to 96 per cent of the heat from the stale air is transferred to the fresh air being put into the habitable rooms of the home. It gets rid of all the VOCs (Volatile Organic Compounds) – a cocktail of chemicals that leaches out of sofas, carpets, laminates, cleaning detergents etc. The main benefits of heat recovery ventilation include:
- Constant fresh air, filtered for pollen
- VOC’s/CO² removed for a healthier environment in which to breathe
- Heating bills reduced by about a third
- Quiet operation
- Decreased humidity levels, so less inviting for dust mites
- No condensation, so mould and mildew don’t grow, prolonging the life of the building fabric
- Exceeds Building Regs
Things to look out for in an HRV system, if you want to put what’s said on paper, into practice:
- PassivHaus certification
- EC motors
- Automatic summer bypass
- Heat recovery figures over 85 per cent
- Rigid metal ducting where possible, which is best for airflows and hygiene
- Correct ductwork insulation
- Controller with 24/7 timing, temperature monitors, SD card for data monitoring, anti-tamper lock out switch.