Wednesday, December 15, 2010


Today, no window can be considered “high performance” unless it can obtain a U-value less than .35. 

Aluminum windows offer the highest design strength that can be used in any high-rise application.    Most manufacturers offer finishes that are environmentally safe with low or no VOCs and are designed with unlimited finishes that can last for decades.  No other window frames can be glazed with the variety of glass options, including security glazing with laminated glass.

The problem is that almost all aluminum framed windows fail to ever obtain a U-value of .40 (R 2.5).  The very rare U-value of .40 in an aluminum window can only be achieved with the use of high-performance triple pane and a thermally broken frame.   

The poor thermal performance of aluminum windows usually comes with extreme condensation problems.  Condensation brings potential water damage and the potential of mold problems on the frames.  In colder upper Midwest climates aluminum frames have even been known to develop ice on the frames.

On cold days aluminum windows frames are considerably colder than the walls or even the glass contained in the window.  This difference in the temperatures will cause drafts.  Drafts make you feel uncomfortable and add more energy costs.

The H Window has the structural integrity to rival and out-perform any aluminum window.  At the same time it can obtain U-values as low as .20 (5).  The  H Window real wood interior performs as a second window.  An extruded aluminum exterior and real wood interior with the latest glazing options set the H window apart from all other so-called “high performance” aluminum windows.

Saturday, December 4, 2010

How Important Is a Window's Air Infiltration?

Did you know that regardless of how well the components of a window functions in providing insulation, its air leakage or air infiltration will negate these insulating features?

I recently had a discussion with an architect about how most window companies fail to disclose the air infiltration ratings of their windows.  The reason for their failure to disclose is obviously meant to hide an issue that would render their insulation rating worthless. 

The best example of this would be the following calculation:

Air Infiltration Calculations:  This is the theoretical amount of air being exchanged based on the test data for the respective windows.  The calculation is based on 5 clad wood casement windows at 20 square feet each and an average wind velocity of 25 miles per hour.  The amount of air leakage is air that will actually have to be heated or cooled to maintain the inside temperature in the building.  (Note that the numbers below are for 100 square feet of windows only.)

Clad Casement Window vs. the H Window Awning - (Air infiltration --lower number = better performance):   
High performance clad casement window:   .20 cfm per sq.ft. = 1,200 cubic feet/hr or 28,800 cubic feet/day.
H Window Awning :   .01 cubic feet per minute per sq.ft. =  60 cubic feet/hr or 1,440 cubic feet/day

Based on this testing, here is an easy example of how this works.    If you have a small home or large room sized at 20’x40’x9’with 7200 cubic feet of space, with 5 average-sized (4’x5’), high-quality clad wood casement windows, facing a sustained wind of 25 MPH, you would have to heat or cool the air in the home or room 4 times each 24 hours.
Under these same circumstances, the H Window awning would exchange the heated or cooled air every other day.

The example above is based on a very high-quality clad wood casement window.  Other operating windows, such as sliding or double hung, would most likely leak even more than a casement window.

Friday, December 3, 2010

What Sets the H Window Apart from Other Windows

WHAT SETS THE H WINDOW APART from vinyl, composite, fiberglass, wood, aluminum wood-clad framed windows is its unmatched thermal performance coupled with the industry’s highest possible ratings against air and water infiltration.
The H Window offers one of the highest possible structural ratings (design pressure) of AW70 with U-Factors as low as .20. 
With the highest structural and design pressure rating, the H Window can provide some of the largest operating and fixed windows in the industry.

The H Window stands alone with the greatest structural integrity for any high-rise building and the thermal performance for any residential application.

Building "Green" involves a commitment to sustainable design. H Window was the first window company to offer FSC woods. As well, the H Window is committed to the LEED building movement.

Our window designs have a proven track record for over two decades in schools, hospitals, governmental buildings and homes. We invite you to examine and compare the performance and appearance of the windows that we manufactured almost 25 years ago to any of our competitors. Almost all of the windows we manufactured over 20 years ago continue to provide high performance and aesthetical quality with little or no maintenance.

Also, as far as replacement windows go, over the years the H Window has replaced many of its competitors' windows -  yet no one replaces the H Window.