15 years? Here’s 15 Passivhaus Myths Demystified
When discussing Passivhaus, people often associate all kinds of common misconceptions with the standard – they want to be able to open their windows, breathe fresh air and not worry about noisy ventilation systems.
Well what if we told you these were all myths and you can have an eco-friendly, energy efficient healthy and comfortable home? Read our 15 points below and see what you think.
1 – You can open the windows
Actually, it is a requirement to have an openable window in every habitable room. You can open the windows, you just might not want to as you’ll be getting plenty of fresh filtered air from your MVHR.
2 – Any building can be a Passivhaus
Although the vast majority are residential homes; schools, offices, museums and even swimming pools have been designed to meet Passivhaus standards. Just like your home, you want your place of study or work to also be comfortable, healthy and energy efficient.
3 – Passivhaus buildings have heating
Nothing is self-heating, and you will always want some form of backup heating. However, Passivhaus buildings are extremely good at retaining warmth, so they only require minimal heating. Passive sources of heat include sunlight, body heat or even putting the TV on – all of which are utilized to reduce the reliance on active heating sources. Some of our clients have installed underfloor heating, but have only needed to switch it on once or twice.
4 – The air is fresh and healthy
Passivhaus buildings have an MVHR system (Mechanical Ventilation with Heat Recovery) which manages the air flow and helps provide a continuous source of filtered fresh, healthy air through the property. Compared to air circulated from an open window, the air from the ventilation system is filtered and actually cleaner; this filtered air is also great for any allergy sufferers as it filters out the pollen so it can reduce symptoms.
5 – You can end up saving money in the long term
Essentially, a Passivhaus standard build can be more expensive than building to basic building regulations, however in the long term when you look at the payback periods, you can end up saving money through energy savings. Housing associations are only reporting a 7% increase in build cost. Along with adding value and energy efficiency to your property, building to Passivhaus standard will improve comfort and help reduce your carbon footprint.
6 – You can pick the look
Passivhaus standards don’t dictate how you build your property, they only implement set requirements when it comes to the technical specifics. Depending on where you live, there will be a construction vernacular (so you just need to check these details); but generally, it will be like building a regular structure with more attention to the comfort and energy efficiency factors.
7 – The ventilation system is quiet
The MVHR units are really quiet, there is actually a Passivhaus criterion to adhere to for a property aiming for certified Passivhaus standard. The MVHR unit must be below 35 dB in the installation room and below 25 dB in the bedrooms. For comparison a whisper is about 30 dB, while talking is about 60 dB and a modern fridge freezer is between 32-47 dB.
8 – A passivhaus must be a new building
You can retrofit homes too. You can read more about Passivhaus for Retrofit on our website.
9 – They stay cool in summer
The levels of insulation required in a Passivhaus actually stop the heat getting in from outside on a warm day. PH criteria requires the overheating risk to be below 10%, but is more usual to aim for less than 3% to allow for the effects of climate change. Overheating is defined as the percentage of time the temperature inside goes over 25°c.
10-They aren’t complicated to design or build
Some people believe that the design of a Passivhaus is complicated, in fact they’re quite the opposite. Compactness of building forms makes it easier to achieve Passivhaus and also to design and build. A simplified form means less detailing.
11-They don’t have to be built from sustainable materials
Passivhaus does not dictate any specific materials to be used or construction system to be implemented. It’s important to make choices best suited to achieving the requirements of Passivhaus, like increasing airtightness and thermal bridging but ultimately material choices are up to you.
12-They aren’t as expensive to build as you may think
According to the Passivhaus Trust, extra costs associated with building to Passivhaus standard have decreased and a new build Passivhaus will only cost you on average an additional 6% compared to a traditional build. It is thought these costs are to decrease further as the standard becomes more widely used.
13-You can have a wood burner…
…you just don’t need one! A Passivhaus will stay toasty through the winters, so usually very little heating is required. But, if you do want a wood burner, as long as it is the right type and installed correctly, there is no reason why you can’t include one as part of your design.
14- Passivhaus is a German system and no-one builds Passivhaus in the UK
The first UK Passivhaus certified in 2009 and figures show that in 2022 there are over 1,490 certified projects and over 7000 underway.
15-They don’t get mouldy
Homes that use an MVHR system and are airtight are actually less likely to form mould than those that adhere to this level of detail. The higher air quality and constant provision of fresh air avoids mould forming.
You can find out more about Passivhaus here and see how we can help with your Passivhaus project.
