Quickslide’s Ade outlines what you need to know about energy efficiency.
‘What do I tell my customers when they ask about energy efficiency?’
Although there is an assumption that all windows will be energy efficient as they have to comply with that little document called the Building Regulations, apparently there is a big difference between what needs to be achieved and what can be. In my experience most homeowners will be happy that their windows are ‘A’ rated according to the rainbow chart used in the Window Energy Ratings scheme (of which more later) and all of our windows, actually, fit that bill comfortably. However, just as very few of us can really understand what the difference will be in the real world between a ‘B’ rated and ‘A’ rated fridge in Currys, then few will really grasp the similar difference with windows. But why even try them with anything else when ‘A’ is standard?
What do the letters mean?
Most people are familiar with the rainbow ‘energy label’ on white goods such as fridges and washing machines. These also apply to windows and doors under a scheme called Window Energy Ratings (WER) run by an organisation called the British Fenestration Ratings Council (BFRC). Our windows and doors are available with an energy rating of ‘A’ which is generally highly acceptable, and way above the minimum defined in the Building Regulations, which calls for an energy rating of at least ‘C’.
Any reputable manufacturer will produce energy efficient windows with energy ratings that surpass the energy efficiency standards set out by Building Regulations but in context, even the minimum ‘C’ rated windows are relatively energy efficient, especially when compared to single glazing.
But if your customer has been reading up on the Internet and challenges you about U Values, windows can comply with part L of the Building Regulations (please check for your own area: Regulations for England, Wales, Scotland and Northern Ireland may differ) by having an overall u-value of less than 1.6W/m2K. The lower the U-value the less heat will escape through the window and the higher the thermal efficiency. Our PVCu sliding sash and casement windows offer u-values as low as 1.4W/m2K.
Triple is better right? Well actually…
Your customers may also throw ‘triple glazing’ into the conversation. However, whilst it might seem logical that an extra pane of glass must improve energy efficiency by 50 per cent, due to some very complicated physics, including the efficiency of some very clever coatings added to the glass during its production, triple glazing offers very small incremental increases in energy efficiency when compared to double glazing. Our triple glazed casement windows can go as low as 1.2W/m2K. But bluntly, what is a slight difference in thermal transmittance between double and triple glazing, will likely go unnoticed, but the difference in cost will not. And when the additional cost of energy used in manufacturing and transporting triple glazed windows is taken into account, any real-world savings are negligible.
PVCu versus Aluminium?
Modern aluminium windows will generally be as energy efficient as their PVCu counterparts. But bear in mind that aluminium – metal – frames will feel colder to the touch, although the overall performance can be similar. Again, to make a useful comparison use the Window Energy Ratings rainbow chart, which is designed to compare products on a level playing field. These days it’s down to preference.
For further information on Quickslide visit https://www.quickslide.co.uk/