Guest post from Mark McLean:
Coming from an energy efficient background, predominantly based around the principals of passivhaus, we have to constantly come up with ways of incorporating the latest glazing gimmicks.
Bi-fold doors over the years have grown in popularity thanks to shows such as CH4’s restoration man and Grand Designs.
These shows always manage to incorporate glazing elements such as bi-fold doors and large format glazed doors, but has anyone of late actually checked the regulations in regards to these systems and had a look at specification sheets of bi-fold door systems?
On the Internet today I have had a look at several manufacturers who all insist that they have some of the most energy efficient systems on the market, however, on closer inspection I have found the opposite.
Considering that the size of aperture the doors are filling you could potentially be forming a large hole in the side of your house, one that could leak water, air and a combination of both a fundamental no no when your trying to create the most energy efficient of homes that is based around the principal of being air tight.
It’s a scary fact, but out of 6 manufacturers that I had a look at, all specializing in bi-fold door systems, only 2 of the door systems actually complied with the current building standards.
2 of the “energy efficient” systems could not achieve a U Value of greater than 1.8 (which does not comply with current building standards, especially in Scotland) and even more worryingly the other 2 manufacturers displayed information on their website in the form of test certificates which openly showed that their systems were only wind tested to around 60 Pascal’s, sounds quite technical and all above board doesn’t it?……….well that’s only around 30 miles per hour!
SO…….when looking into bi-fold doors for new build or replacement projects check the test certificates for the following factors:
- What have the doors been tested to in terms of wind speed? In the UK I would advise something around 2000 Pascal’s or even 300 Pascal’s (that’s around 160 mph.
- Have the doors been tested on the basis of air tightness, if so this is not enough, doors need to be tested to wind and water tightness, in the uk we rarely get wind without rain.
- What have the doors been tested to in terms of weight capacity? Check the weight of the single sash (manufacturers have to show this) then check the capacity that the roller can take in terms of weight
- Is the door CE marked? This is a fundamental requirement now, a lot of manufactures are now buying in extrusions from abroad and then building the doors in the UK, but IMPLYING that the doors are manufactured in Germany etc.
- What’s the best U Value that the door can achieve? Get to know your regional glass regulations, understand what your building control department requires of your build, in terms of energy efficiency I would suggest that you want a u value of lower than 1.4 preferably 1.3 if possible, there are manufacturers out there that can produce doors to the Passivhaus standard 0.8 but these doors do come at a premium price point.
- Have the coatings (if Aluminium Clad) been tested to withstand coastal conditions? if your installing these doors in commercial locations, like restraunts bars etc, a lot of these place like to take advantage of sea views etc, this is something to bare in mind, there’s nothing worse than installing a door and then having to go back 2 years later to remove it because the mechanism has rusted solid.
- Finally, and most importantly, does the door have toughened glass? Yes I know this may be obvious, but some of the system’s are tested with float glass in place instead of toughened, toughened glass naturally has a lower U Value due to the reduced light transmittance and lower solar gain, but you can install doors in the UK without toughened or laminated glass.
If you need help and assistance in relation to “energy efficient” Bi-Fold door systems get in touch via the website and I can point you in the right direction of the very few doors which do tick all of the above boxes.
Don’t get me wrong, they are not the cheapest on the market, but with the average bi-fold door aperture being over 3.5m wide and over 2.1m high air tightness and build quality are quite an important factor to consider when spending our hard earned British pound.
Blog By Mark McLean: Director, Callum Walker Energy Source
This is an Interesting but factually flawed post. A u value of 1.8w/m2k does indeed meet the requirements of Part L, although it is correct that Scotland requires an improved value of 1.6w/m2k. Although there is a British Standard to test windows and doors to (BS6375-1), this is not a compulsory requirement to test to even under CPR/CE Marking (weather testing is not mandated). The highest weather exposure category that you can test a door to in BS6375-1 is 1200Pa, although windows can be classified upto 2000Pa. British Standards only cover performance characteristics (weather, security etc.) To guarantee longevity the… Read more »
I agree in part with what your saying phil! New build homes in Scotland require a U Value of 1.4 now, replacement is 1.6 unless other arguments or compensatory U Value calculations can be provided to state otherwise. In terms of whats required and what SHOULD be required…..well thats another story all together, it may be that in scotland we are subjected to slightly harsher weather conditions and elements of exposure, thats why i was saying that although British Standards state that Doors should be tested to a certain compliance its not necessarily enough. The key elements that i’m trying… Read more »
These seem like important factors to look for when checking out bi-fold doors. It’s very important to me to make my home as energy efficient as possible, so it would be good to know that I can get bi-fold doors that are made to be energy efficient. It would be very good to know if a door has been tested to withstand weather conditions and have toughened glass. I live in an area that has really rough coastal conditions, so it’s important to me to have a door that can stand the test of time.
Is it possible you could post links to the doors that Do meet your recommended standards? Clearly you’ve done some valuable research and this would save both myself and others considerable time trawling the net trying to suss out which doors are worth looking at and those which are not
I’m hoping to put an extension in the back of my house which will create a large kitchen diner.
I’m concerned re heating and energy costs so looking for the best solutions for bi folds and possibly underfloorheating