Passivhaus And Covid 19?

September, 2020 |

Since COVID lockdown we have had one or two specific queries around ventilation implications with Passivhaus. My partner has an autoimmune illness, so Covid is a concern for us, and we review regularly where our risk boundaries lie. One worry has been around air conditioning and the potential that the virus might be recirculated within internal spaces, especially where there is minimum refreshing of the air from the outside. We are both quite wary, for example, of small shops or restaurants with enclosed spaces and the air-conditioning on.

What about MVHR?

Minimal energy use relies on a good mechanical ventilation strategy (MVHR). The typical certified ventilation units used for Passivhaus conserve up to sixteen times the energy required to run them, so a mechanical ventilation system with heat recovery is an integral component for achieving extreme energy efficiency. But what about any health implications at a time we are anxious about air quality and the spread of a virus that comes with serious health risks. If you live in a Passivhaus already, is your MVHR system a positive or a negative? Should you turn your MVHR system off? If your dream is to live in a Passivhaus standard home, is the MVHR solution associated something to now cause you concern?

The key difference with MVHR is that the internal air is not recirculated at all – the unit is only supplying 100% fresh air from the exterior. The heat recovery works by passing the incoming and outgoing air through many adjacent narrow passages, the air being separated by very thin walls, usually made from metal or plastic (the heat exchanger). There is no mixing of the air itself. Older air in the house is being constantly removed to the outside and being replenished by new fresh air. The fresh air is quietly moving from the living spaces, where the supply outlets are located, to the wet and smelly spaces (e.g. bathrooms and kitchens), where the extract outlets are located. The system runs constantly, not intermittently, so there is no chance for stale air to build up. An energy efficient house with a good MVHR system will reduce transmission risk in an interior space for someone with a high risk to COVID – especially in the colder months when the windows are likely to be closed. A Passivhaus café would be a safer café to have your cappuccino or latte in!

On discussing this with my partner she advised I should immediately write this article and advertise it on our website! Some of our current PH15 clients are older and therefore with higher vulnerability to COVID. COVID is unlikely to go away soon, sadly, and similar virus outbreaks may well become more common in the future. Three out of four new infectious diseases now originate in animals – zoonotic diseases – impacted by the animal-human interface increasing under resource pressures and climate variation causing spatial shifts in habitat location.

Co-benefits

This has reminded me again of the co-benefits that a core action can bring – one good decision frequently leads to so much more. The good sense in adopting the Passivhaus standard can be argued without the need to include climate change mitigation because the co-benefits are so many. This observation around virus transmission is just another of these co-benefits. Passivhaus is the application of building physics, and physics is simply the knowledge of nature and how it behaves – so these co-benefits should not be a surprise. We exist within eco-systems that are built upon multiple interconnections. Good or bad actions are therefore likely to create diverse outcomes and we commonly underestimate the reach and breadth of the impacts of our economic choices. Passivhaus forms part of a new ‘low carbon’ economy, and it is a great example of the co-benefits of creating the right sort of economic growth, rather than ANY economic growth