WHY BUY ENERGY EFFICIENT WINDOWS?
1. Independent studies conclude
that using low-e glass and using a low conductance gas such as argon may improve the energy efficiency of a window 100% over
2. Homes may lose up to 30%
of heat or air conditioing through its windows.
to PSE&G, for every 1° F increase on the thermostat, energy use increases 2%.
4. The ROI on upgrading to Energy Star® rated windows can be as soon as 2 years and at most
10 years, while the expected life span of the window is a minimum of 25 years. As soon as 2 years, these
windows can actually make you money!
HOW DO WINDOWS LOSE
Conduction: The transfer of heat through a solid material.
A. The less conductive a material
is, the less heator cold will transfer through.
2. Convection: Movement of heat froma hot to cold region
A. The cold outside pane of glass meets a warmer surface on the heated inside pane.
When this happens,the air against the inside pane of glass cools, becomes dense and drops to the floor. Often, this
felt as a draft when in fact, it is the interior house air currents rotating. Warm air rises, cool air drops. The circular
movement can be felt as a draft.
3. Radiation (Radiant Heat): Movement of long eavelength heat energy froma warmer body to a cooler body.
A. In the winter, glass absorbs head
and radiates it outdoors.
B. Inthe summer,the suns rays (UV and IR)heat your house from the outside. This is called solar Heat Gain or SHGC (solar
heat gain co-efficient).
Air leakage: Leakage of air through winows via surface intefaces of the window
A. Glass to sash
B. Sash to frame
C. Frame to frame.
HOW DO YOU COMBAT THIS?
1. Upgrade from clear single or insulated glass to a Certified Energy Star® rated Warm Edge glass package which should contain:
1.. A slightly tinted transparent metallic oxide coating is applied to the glass. In the cooling season when the
sun is high in the sky with a high angle of incidence, this coating
results in a reflection up to 90% of the sun's long wave heat energy (UV) back outside the house.
2. In the heating season when the
sun is lower in the sky with a lower angle of incidence, it reflects long wave radient heat back into the house where the
energy is absorbed
by the walls, floors, furniture,etc.
3. Allows visible light to pass through
4. Improves insulating value as much as adding another pane
of glass (storm window)
B. Low Conductive Gas (Argon)
5. Pumped under pressure between
two or three panes of glass. this gas forms a barrier preventing the conduction of heat or cold through the glass.
inert, non-toxic. It's in the air we breathe.
C. Use of non-metallic (aluminum or steel)
spacers such as Super Spacer® that separate the glass panes from each other prevent conduction through the
edges of the glass panes.