IMAGE CREDIT: Charlie Luxton Design
Charlie Luxton, architectural designer and TV presenter, has worked with Airflow to document the MVHR heating and cooling installation done at the Charlie Luxton Design Black Barn Studios. He discusses how MVHR can be a great solution in providing a comfortable, low energy space:
“I've worked with Airflow for a long time and for a number of reasons. One of the main ones is that they cater for very small projects right up to very large projects. A lot of their kit is also Passive House certified, which is a really good mark to have on any unit.
“We wanted to create a very low energy building, both in use, so Passive [House] equivalent, and in construction, so we were focused on the amount of energy that we use to make and run the building. It's incredibly well insulated, and we’ve been using mechanical ventilation with heat recovery, MVHR, for many years. Once you have a highly insulated and airtight building, providing fresh, clean air becomes a large component of your overall energy use, because you're losing so little energy through the walls - but you can massively reduce this by using MVHR.
“Beyond the energy side, MVHR increases the ventilation levels that you would normally get in a building, so you get air that's fresher and filtered.
“We use an air source heat pump to provide heating through a DX coil on the supply side for the air. As the air comes in, we warm it up, bringing the heat into the building. What's fantastic about that is that in summer you can run the air source heat pump backward and cool the incoming air. Even in the middle of winter, the amount of energy used is minimal; we're using only about one and a half kilowatts of electrical energy.”
The benefits of MVHR
“MVHR removes a lot of particulates; not only from cars and wood burners, but also pollens, which have really helped with allergies. It also keeps the humidity lower and more stable, normally at around 50% to 60%. Any higher than that, you start to moving into the realms where you might get black mould.
“The MVHR unit communicates with our building management system, so I can access data about how the building is performing and see the CO2, humidity and temperature in all the different rooms. We can then use that information to control the MVHR to try and keep the temperatures as comfortable as possible.”
Solving the problem of overheating with MVHR
“Overheating is something that we've been looking at with real focus for about eight or nine years. If a building is cold, you can turn the heating up. The big issue is that when buildings get hot, it is much harder to solve that problem.
“People start putting in air conditioning, but full on air conditioning is very energy intensive. We can reduce the demand for that just through good, thoughtful design. Part O deals with that. You now need to thermally model all of your buildings to understand that they're going to overheat.
“When we're designing buildings with MVHR, we start integrating the MVHR system as early as possible in the design phase. It's really not complicated if you think about it early, and then when you get to site, it should go really smoothly.”
Alan Siggins, indoor ventilation expert and Managing Director of Airflow, explains MVHR:
"MVHR is a type of ventilation system that uses mechanical means to supply fresh air to a building while simultaneously extracting stale air – and moisture – from the building. The system works by using a heat exchanger to transfer heat from the outgoing air to the incoming air, which helps to reduce the energy required to heat or cool the building.
"MVHR systems are usually used in buildings that are highly airtight, particularly those that require a greater level of air quality and energy efficiency. MVHR has numerous health benefits and keeps spaces free of mould and other harmful growths – all while providing a cost-effective, more sustainable ventilation method.
"While MVHR systems are intricately designed, they are low-maintenance and operate automatically, sparing occupants from manual fan and temperature adjustments. A demand control function detects when moisture or extra carbon dioxide is being produced and boosts the level of ventilation."
