IN’FLECTOR – The See Through Radiant Barrier Window Insulator
Reducing our ecological footprint is an essential part of getting to a more sustainable future and one of the best places to start is the home.
Approximately 43% of your utility bills are for heating and cooling and about 12% is for hot water. Our topic for review here will be about the heating / cooling of your home and specifically about a product than can make a dramatic difference in your heating and cooling costs and to your personal comfort.
To get the best effect from any heating and cooling device in a home, the first thing to deal with is the building envelope consisting of the foundation, exterior walls, roofs & windows.
The way the overheating cycle takes place is that the sun shines on the exterior of the house and heats up the mass of the wall which ultimately radiates the captured heat into the house. If windows are not covered or protected, the sun heats the house interior directly as well.
Using insulation slows the heat penetration but provides mass to retain and hold the heat longer. Different insulation work in different ways which we will examine at another time. Suffice it to say that reflecting the heat away before it gets to the insulation and the wall or roof mass, would be a very effective way to deal with overheating. That applies to roofs, walls and windows.
The cooling cycle – Heat travels to the cold and our wall and attic insulation helps here. Again the effectiveness varies by materials but this is another conversation.
Our focus today will be the windows because they are one of the biggest “leaks” in the house envelope. Your wall might nominally be R15 to R20 and attic R20 to R40 with insulation but your windows will be as follows. (We will use R value as the measurement as it is a familiar term for comparison purposes)
Most homes (at least in Canada) have double glazed windows of one kind or the other, so we will start with a typical double glazed window (meaning two pieces of glass). We are going to be speaking about just the relative value of the glass because the frames of windows will make a difference to the efficiency as will the installation, type of window and other factors. We are also going to speak in general terms in order to explain things on a conceptual level. Specific windows and products will vary but the following provides the basic information.
Ordinary double glazed windows have an R factor of R 1.3
Double glazed windows with low e (low emission) coatings and argon gas will produce an R factor of R 3.2
Triple glazed windows with low e coatings and argon filled air spaces will achieve up to R 7.9 or more than double the efficiency of double glazed glass. Usually the premium is not double the cost and often worth looking at for the energy savings and comfort; if you are buying new windows.
As you can see the thermal rating of windows does not even get close to a wall’s thermal rating. The result is heat loss in the winter and heat gain in the summer months. Curtains are generally used to mitigate this inefficiency.
However, many modern homes have large expanses of glass for the light it provides. An unfortunate consequence is that it can be uncomfortably cold in the rooms with large windows in winter and overly hot in summer. These swings are balanced by heating & air-conditioning devices. These cost you money and expand your carbon footprint.
A number of products have been developed to deal with this including some very thermally efficient curtains and external shutters like Rollco Rollshutters http://www.rolco.com/store and whole house fans can help with cooling. We will talk about this at another time.
A unique product has been developed specifically for this which optimizes window use beyond the previously mentioned options called In’Flector – The See Through Radiant Barrier Window Insulator. It is essentially a screen type of material which is reflective on one side and dark coated on the opposite side. And it can be fabricated for use in a number of formats including a screen in a metal frame for the whole window, a roll down shade, or vertical shades.
The material is reversed for summer or winter use. In our climate the reflective side would be out reflecting summer heat out before it enters the house and in the winter the reflective side is in to reflect heat back in so that the heat is not lost.
An additional bonus is that the black side acts like a solar collector in the winter and transfers heat from the winter sun into the house while at the same time the reflective side is reflecting the heat back in.
Independent testing concludes that it can add 50% to your windows’ efficiency and the solar gain of a 4×4 window is equal to a 2096 BTU/hr or a 600 watt heater for free heat in the winter, so the payback on this can be fairly quick depending on window sizes and other factors.
In some cases it may be a great alternative to replacing windows; and it can definitely make your current windows more effective and increase your personal comfort. For more information on the In’Flector – See Through Radiant Barrier Window Insulator you can go to their website at: www.energyefficiencydr.com
For other “green” product reviews See Tech Talk at the Coville Challenge website