9 Passive House Myths

We’ve chosen 9 of the most common Passive House misconceptions with the hope that we can debunk the folklore, once and for all.

We’ve chosen 9 of the most common Passive House misconceptions with the hope that we can debunk the folklore, once and for all.

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This has to be fictitious because nothing can heat itself. The point is that Passive Houses retain any generated heat very effectively – but this heat still has to come from somewhere. The Passive House standard sets a criteria for the space heating energy demand of a dwelling at <15kWh per square metre of living space. A duct-mounted post heater or small boiler is usually sufficient to meet this demand.

9. A Passive House heats itself

8. There is no such thing as an attractive Passive House!

This is simply untrue. As of 2013 estimates, there are over 50,000 Passive Houses worldwide and they come in all different shapes and sizes. As the first dwellings to achieve the standard were found in Germany and Austria, there was a certain common local aesthetic which may not appeal to everyone. Since these were the buildings to attract all of the publicity, this may have led to the misconception that all Passive Houses have to look this way. In practice, there are certain building forms which more easily achieve the standard but, in reality, your Passive House can look any way you choose.

7. Heat recovery ventilation (HRV) costs more to run than the energy it saves

False! When HRV systems are properly installed, the ratio of electricity required to heat loss prevented is 1:10 or better. In other words, the ventilation system saves more than 10 times the energy that it requires for operation. And that’s all I have to say about that!

6. Passive Houses can only be built on sunny sites

Incorrect – a shaded site is not an excuse to dismiss the Passive House standard out of hand. Passive Houses can be found in inner cities with a northerly aspect. Admittedly, you would face more of a challenge as Passive Houses are designed to optimize, and benefit from, solar gain. However, the Passive House Planning Package (PHPP) is the key to ensure that all of the site requirements are met to achieve the desired result.

5. Mechanical ventilation with heat recovery (MVHR) is too complicated

I’m sure that people thought the same thing when first introduced to gas central heating in the 1970s – but we soon got to grips with that didn’t we? The truth is that MVHR is no more complex than a central heating boiler. With a simple handover, anybody can understand the intuitive controls. Also, ventilation with heat recovery isn’t the new kid on the block that people think it to be. The technology has been developed, perfected and simplified for over 50 years!

4. The ventilation system is too noisy

Well this is potentially a myth but it all depends on the quality of the design and installation – done properly, the fans run at such low speeds that there should be very little noise anyway. Plus, the Passive House criteria demands that any noise generated should not exceed the levels that the World Health Organisation recommends in order for people to sleep comfortably. If there is the possibility of cross-talk (where sound travels from room to room through the ducting network) then a radial ducting system can be employed to overcome this.

3. You can’t refurbish an existing house into a Passive House

Okay, okay – perhaps not a fully-fledged ‘myth’. Undeniably, it is more of a challenge to achieve. Fixed aspects of existing buildings – fixed form, fixed orientation, planning/conservation restrictions – can mean that the full standard isn’t feasible. However, you can build Passive House technology into an existing building. Through improving the building fabric and services you can still achieve real energy demand reductions. For this reason, the EnerPHit standard was introduced in 2010. This slightly relaxed energy standard is awarded when modernization to full Passive House standards wouldn’t have been practicable or cost-effective.

2. The Passive House standard doubles the cost of building a new home

As the popularity of the standard increases, the cost to build continues to decrease due to a greater availability of the products (and people) needed to build them. The latest estimates show that less than 10% extra investment is required.

Passive House is a quality assurance standard – what is designed is precisely what you get so the quality of components and workmanship must be up to the task. Compare this to a home built to meet standard UK regulations (where there is little assurance that the finished product will resemble the initial design in terms of quality) and it is easy to see how this cost myth keeps being perpetuated. If all new builds were constructed as designed – they’d cost more too!

And finally (drum roll please) the most common Passive House myth is…….

1. You can’t open the windows in a Passive House

Obviously, the highly coveted number 1 spot had to be saved for this old favourite!

Have you ever heard of a Passive House that has been designed to have its windows sealed shut? No, me neither. In my experience they have windows that open like, well, windows! The mix-up seems to be that, with a Passive House, you don’t NEED to open the windows. The ventilation system works to bring the perfect amount of fresh air in so that you never find stale air in the home. Our Technical Services team come across this misconception so often that our Senior Technical Advisor wrote a blog piece devoted to this topic – read it here.

So, there we are – the countdown is complete.

Hopefully we uncovered all the untruths that you regularly come across. If not, why not contact us and let us know which bogus claim you would like us to expose?

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