The performance of Irish buildings has been blighted for too long by failure to deal with our damp climate, combined with massive, avoidable heat loss. Heat recovery ventilation (HRV), a technology that has become a standard building application in Scandinavian countries, is rapidly gaining recognition in Ireland as a solution to both problems.
This feature aims to give you the lowdown on HRV, helping to educate on how the system works and which type of system is suitable for you. We will cover the following topics:
- The Dilema – Heat loss versus fresh air
- The Solution
- The Benefits
- The Costs
- Can a HRV be fitted in an existing home?
- HRV in New Builds
- Single Units
- Air Changes
- General Design Considerations
- Additional Points to Consider
Most of us are aware that one of the first steps in increasing the thermal efficiency of our home is to insulate, insulate, and then insulate! In this process, many of us are putting increasing emphasis on ‘sealing’ our homes to prevent heat loss. Having done this, we then need to ventilate so we put a hole in our wall or window. Doesn’t make sense, does it?
The current building regulations for ventilation, Part F1, stresses that the main functions of a ventilation system on a general level should:
‘provide an adequate supply of fresh air for using an area or building; achieve occasional rapid ventilation for dilution of pollutants and of moisture likely to produce condensation in habitable rooms, kitchens and rooms containing sanitary appliances; and extract moisture from areas such as kitchens and bathrooms, where it is produced in significant quantities’.
The majority of homes and buildings in Ireland are fitted with wall or window vents. This allows valuable heat to escape and creates draughty rooms. According to Kirk Shanks, a research engineer with the Energy Research Group, who is actively researching developments in ventilation, “between a third and half of an Irish building’s heat loss typically occurs through cold air exchange”.
However, ventilation plays a key role in the health of occupants and the structure of a building, and there are consequently minimum requirements set out in part F1 of the Building Regulations. We need ventilation to ensure a healthy living space. There is a significant increase in the number of people suffering from asthma and other respiratory problems aggravated by poor air quality. The dust particles, mites and bacteria in the air are not visible to us. Even if you are not a sufferer of a respiratory ailment there are other symptoms of poor air quality such as, drowsiness, aggravated sinus, headache, eye irritation, skin irritation and a general lethargic feeling.
From a structural perspective, a lack of quality ventilation can be extremely destructive. The most obvious sign of poor ventilation is condensation, which is most commonly visible on cold surfaces such as windows. However, condensation can also occur in other vital constituents of a building, such as masonry or timber. Here moisture is easily absorbed, and with continued accumulation problems such as rot, mould, and deterioration of decoration are likely to result. A HRV will combat this problem by completely drying out the actual framing, insulation and interior cladding of the structure. The system will also dry out damp furniture, curtains and carpets.
An apparent dilemma exists here, as buildings are required to both retain heat, and circulate air. How can modern buildings fulfil their energy requirements and provide adequate air circulation at the same time when each function seems to undermine the other?
Find out how to overcome this .