I live in a Dublin estate of three and four-bedroom semi-detached houses in a low-lying area beside the sea. The houses were built in the 1980s and all have fireplaces. Our house has gas-fired central heating, so we have never used solid fuel since we moved here about 10 years ago. Our problem is that the area is often afflicted with a heavy smell of burning coal which can make the air both inside and outside our house really unpleasant to the extent that we feel ill.
We have tried to remedy the situation by putting in triple glazing and a tall covered chimney cowl from Germany which is supposed to stop the foul air from coming in to the house. We did this after doing a lot of research on the effects of temperature inversion. While it works most of the time, sometimes the pollution does come into our home. We think it is coming through the air and window vents that we are obliged to have, and possibly through the chimney as well.
Is there anything we can do apart from blocking up the chimney and the air and window vents completely? Are there air purifiers that would do the job? It would be yet more expense but probably worth it to feel less ill.
Before looking at your specific query in detail it is important to note that a ban on smoky fuels would address the wider issue of pollution, which affects your area – and many others like it. This is the root cause of your problem. Unfortunately, such a ban is unlikely to be implemented in the short term because many people in fuel poverty rely heavily on coal.
You have already identified that improving the air tightness of the house will help your internal environment, the open chimney probably won’t help as it creates negative pressure so draws outside air in through remaining gaps and the requisite wall vents meaning that internal filter systems are unlikely to help.
The danger for a sealed airtight house is that most occupied rooms need to replenish the air volume up to three times an hour to maintain a healthy air quality, hence the holes in the walls. If all are blocked up then some form of mechanical ventilation system is necessary.
The great advantage of such systems is that inbuilt filters dramatically reduce dangerous particulates in the incoming air and can remove anything from smoke particles, airborne dust, bacteria and allergens such as pollen. At the same time these systems will expel internal pollutants such as dust, mould spores and volatile organic compounds (VOCs) found in many household items. Removing the odour from incoming fresh air is more difficult but some systems have the ability for activated carbon filters that can help reduce the smell in incoming air naturally.
Another advantage of such systems is that they can dramatically reduce your heating costs, particularly so with double duct units with heat pumps included that recover 100 per cent plus of your energy to the extent where your gas boiler might be redundant if your house is also well insulated.
The cost of mechanical home ventilation (MHV) systems vary considerably and depend on how your house can be fitted with ducting, however, the advantage to improving air quality and your health could well be priceless.
Fergus Merriman is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie
