“RAS Engineering strives to test the performance of building elements used during restoration of buildings to provide high performance results with the belief that testing and discovering energy efficient solutions with high payback is not only possible but makes financial and economic sense.”
RAS Engineering is introducing the revolutionary backup glass frame system, manufactured by GreenB. This system gives unit owners the freedom to choose their window features, without replacing the existing window. It’s a great solution for unit owners that want and need to replace their windows but are prohibited by Association or Code Regulations. The backup glass frame system allows for exactly what you want in a window and much more.
The envelope of a building which is the exterior surface of a building is the shield protecting the occupants from the environment. In addition, elements like windows have a great impact on air conditioning performance and drastically affect the energy efficiency of a building. An innovative product on the market called a backup glass frame is a sustainable solution to restore the envelope saving expenses in various ways. The revolutionary glass frame has several distinctive features: first, it allows for high impact. This is valuable in the event of hurricane winds preventing breakage or blast explosion. The backup window also has extra sealant and insulation inside on the frame, meaning there is no contact in between the metal of the window with the exterior. This prevents thermal bridging that transmits the heat from outside onto the metal, reducing transmission of heat, sound, infiltration of moisture and pollutants. Also, airflow is blocked by the backup glass frame preventing pollutants and air leakage.
In this video, RAS performed an air infiltration test on a backup glass frame and a standard window in order to show the benefits and savings in comparison. A standalone wall with two window frames, referred to as a Mockup, was constructed to test windows. The top window was fitted with the backup glass frame system, while the bottom window was left as a standard brand new window. A blower is connected to the air chamber by flexible ductwork. The chamber is attached to the wall using the clamps for a tight seal. The blower is turned on and the pressure gage is set at 50 Pascal’s to test the upper window with the backup window installed. The testing tablet attached to the mockup automatically calculates the annual cooling cost for this window with the backup glass frame: which comes out to $5 per year per window.
The chamber is then disassembled and reassembled to test the bottom standard window. The pressure gauge is once again set at 50 Pascal’s as the blower is turned on. The difference is almost an extra 300 cfm passing through the bottom window into the interior of the room. This airflow was blocked by the backup window on the first test. The results of the testing show the annual estimated cost of air leakage is $37 per year in cooling alone for a small window of this size, and of course the cost of wasted cooling air and energy will rise on windows of an even larger size.
We are now going to place the results of the test into a chart.
The perimeter of the standard window is 86 inches, and the test concluded that the annual infiltration rate came out to be 37.6 cubic feet per minute. If we divide the infiltration rate by the perimeter, we find that there is about 0.44 cfm per inch of caulking. The cost of air leakage per year results in 43 cents per inch of caulking. Reviewing the annual infiltration rate from the backup window, the infiltration was only 4.5 cubic feet per minute, which in this case divided by 76, which is perimeter of the caulking on this window, we reach 0.06 cfm per inch. The cost of air leakage per year in this case comes down to 5 cents per inch of caulking.
Now we will use an example of backup windows installed in 3 rooms in Miami, FL with a size of 6’x4’ approximately.
The caulking perimeter of the standard window would be 1,222 inches and in the backup window, which has less caulking than the standard, it would be 720 inches. We are going to apply the calculated value of cost of air leakage from the first chart for each window, and, assuming 10 cents per kilowatts hour, we see an annual cost of $526 for the rooms with standard windows. In comparison, the rooms with the backup windows would only cost 36$ per year. This gives us a savings of $490 per year on the infiltration of air for just 3 rooms.
While the results are impressive. this is only one of eight demonstrating the economic benefit of high-performance buildings. The payback on this innovative product is about one year. Additional benefits will be revealed in future episodes: Pollution Control, Thermal Heat, Solar Radiation, Waterproofing, Air Humidity, Hurricane Impact, and Financial Payback, in addition to Sound Insulation (which cannot be quantified in dollar amounts).