Clarissa Youden from Total Home Environment discusses how super-insulated and airtight building fabrics have seen the use of Passivhaus-certified systems that go ‘beyond’ MVHR to harness the benefits of heat pump ventilation.
Imagine the appeal of a new home which does not rely on an air source heat pump outside disturbing the peace, or a social housing project that doesn’t need district heating that’s prohibitively expensive-to-maintain? Now, a home can recover all waste heat and have responsive, energy efficient space heating and cooling, all without a formal heating system.
This is no longer simply the domain of the bespoke eco home, but a reality that has been made possible by advances in mechanical ventilation with heat recovery (MVHR) and the development of heat pump ventilation (HPV).
It is well known that one of the best things to reduce carbon emissions in homes is to conserve heat by investing in a better insulated, airtight fabric. In doing this though, air quality is compromised, and especially after Covid, there is more awareness of the dangerous compounds that can be trapped in the air. The solution is normally MVHR, but it is possible to go a step further, with HPV which combines mechanical heat recovery ventilation with an integral heat pump(s). The technology doesn’t require pellet storage space, ground-drilling, inconvenient radiators, underfloor heating pipes or planning permission.
How does heat pump ventilation work?
The HPV unit is normally located in a plant room, utility, cupboard or loft area and connected to rooms via rigid metal ducting and ceiling terminals. Like MVHR, HPV silently extracts stale warm air out of kitchens and bathrooms and then recycles the heat into fresh filtered air. The integral heat pump then adds energy efficient heating (or cooling) to the air supplied to bedrooms and living rooms. Typical COPs (Coefficient of Performance) of between three and seven can be achieved in comparison to gas at only 0.9.
If needed, the HPV Series can also regulate heated ceiling terminals or radiant heating panels for convenient room temperature control with quick response times to ‘top-up’ the heating. While underfloor heating offers a great level of comfort underfoot for residents, they can have instant control and year-round comfort with heat pump ventilation.
It is still useful to have heated towel radiators in bathrooms and WCs (although the heating output needs to be carefully watched, so they don’t overheat) as being extract rooms, they would not be supplied with warm air. A small wood burning stove or focal point fire in a sitting room can also bring comfortable temperatures up to cosy levels, and be aesthetically pleasing.
All domestic hot water comes from air-to-water heat pump in this scenario; the HPW 300 for instance, which is a pre-plumbed 300 L water cylinder with integrated heat pump also has a secondary coil to provide for up to 20 m² of wet underfloor heating in bathrooms, or it can accept heat from a solar thermal heat source, so even the heat pump doesn’t need to heat the water in the sunniest months.
For smaller homes like townhouses and flats, the Passivhaus certified Pichler PKOM 4 compact service unit could be specified, as it performs all of the functions of the larger model, but in one compact box – so suitable where floorspace is at a premium.
If homes are going to be increasingly well-insulated and air-tight, then MVHR is essential. However, by utilising the ventilation infrastructure for heating and cooling purposes too, heat pump ventilation can assist homeowners and specifiers in reducing build time, the number of trades on site and installation costs, all while meeting those all-important carbon reductions.
The principle behind heat pump ventilation is grounded in health and sustainability, but importantly, conserving and recovering more heat initially using this combined technology, means that less heat needs to be generated in the long term.
Benefits of Heat Pump Ventilation
- Energy efficient heating with COPs of three to seven
- Energy efficient cooling with EER of 4.5
- Circa 1,000 litres of energy efficient hot water per day
- Supplementary heating efficiently controlled with quick effect
- Constant fresh air filtered for pollen & allergens down to 0.01 microns
- Heat recovery ventilation
- No separate heating system required (if home well insulated & airtight)
Clarissa Youden is associate director at Total Home Environment