What Is HRV?

The Dilemma

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. Between 33-50% of the building’s heat loss will occur through this form of natural ventilation. But 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.

Therein lies the dilemma. Buildings are required to retain heat, but circulate air. Is one compatible with the other?

The Solution

Yes, amazingly heat retention and ventilation are compatible and the solution lies with Heat Recovery Ventilation. Heat Recovery Ventilation (HRV) is not a new technology, but is only now gaining popularity in Ireland. Originally a Scandinavian product, the HRV system is an extremely efficient, health-beneficial, cost effective solution to saving energy. The HRV System will provide a continuous supply of clean, fresh, filtered air while at the same time recovering and re-distributing heat throughout your home.

1. Heat Transfer Unit
2. Fresh Air Outlet
3. Stale/Contaminated Air Inlet

The HRV unit will sit in your attic (typically) and is connected to the outside by 2 lines of ducting- one to supply fresh air and one to expel stale air. The ducting is connected to your rooms by small ceiling valves. The first line of ducting extracts warm, moist, stale air from areas such as kitchens, bathrooms and utility rooms and expels it outside. However, before doing so the HRV unit absorbs the heat of this air in its heat exchanger. The fresh air coming in from outside is filtered, warmed in the heat exchanger to 97% of the heat that went out, and then supplied to rooms such as bedrooms, the study, playrooms etc. As both the supply & extract ducts remain separate at all times, no cross contamination occurs. A good HRV unit will come with a Summer Bypass to ensure your home or building remains cool during hot weather.

The Benefits of a Good Heat Recovery Ventilation System:

  • Enables draft free ventilation
  • Delivers pure fresh filtered air 24/7
  • Helps re-distribute heat throughout house with a high rate of heat recovery (up to 97%)
  • Has Pollen Filters to reduce allergies caused by dust or stale air (e.g. Asthma)
  • Silent operation
  • Eliminates condensation, Prevent mould, and Removes Radon