rancov's blog

When considering the purchase of new wood windows for your home, take some time to ask if the wood in those windows comes from managed, certified resources. These days, many manufacturers source most, if not all of the wood content for their homebuilding products from managed forests under the FSC (Forest Stewardship Council).

Using wood is beneficial from many standpoints:

Wood is a natural carbon sink.

It is a renewable resource

It takes less energy to process than vinyl

It produces less pollution.

Investigate whether the window manufacturer has any commitment to green building objectives . Using wood windows provides a resource for many people to earn a living. Using the resource responsibly is becoming easier as companies focus on carrying the message about how they maximize their resources to produce quality products, efficiently. Custom windows are no exception.

Energy Star Qualified windows obtain such qualification based on attaining measurements for SHGC and U-Value within certain parameters designated for the particular zone in which the home resides. This is as valid as method of gauging the relative merits of a particular window but misses the point from a holistic perspective when one considers the specific overarching mission of a window.

Specifically, a window's intended function is to support the well-being of the inhabitants of the structure by filtering harsh light, resisting the penetration of cold or heat or water into the structure and providing ambient light for the conduct of the day-to-day tasks all of us undertake to maintain our lives. But that this definition lacks refinement, measure relating to the gain of heat and cold into the house are insufficient to make an overarching judgment of the performance of a window to a specific installation.

There is one additional metric applied in testing for SHGC and U-Value that must be accomplished for the all-important Energy Star ratings, that measure is air-infiltration. Air-infiltration is good in that it allows for the exchange of polluted air with fresh air which is critical to the well-being of the inhabitants, but bad as allowing its natural occurrence in a structure without controlling the finite impact of it leads to a couple of bad impacts such as:

• The installation of HVAC plants oversized for the specific structure.
• The seemingly finite intrusion of cold or warm air that can translate into significant impacts on energy consumption.

We are approaching a point in the consumption of carbon-based fuels where we will have to consider to the finite, the waste of energy, for economic and political reasons. Therefore, we are going to have to understand what impacts air-infiltration has on a home and where that air comes from.

For instance, current day casement windows, compared to current day double hung windows allow air infiltration at a rate of 3%. That is a factor of 30 times less for the casement. This air has to be heated (or cooled) so understanding the totality of the impact of air infiltration on a house is critical to making the finite decisions that may not have such an immediate payback. You may want to consider installing and air-to-air heat exchanger that adjusts the temperature of incoming make-up air with waste heat from the house and restricting down to t the lowest level obtainable the natural air-infiltration of the house.

If you are shopping for windows, ask your professional you are dealing with to do an air infiltration analysis for you based on your plans. If he cannot put one together for you, you might want to find one who can. In any event, once you actually see such an analysis, you might be very surprised at what you find. Changing the air once every 2 days versus 3 times a day in your home can have a dramatic impact on your energy usage. 

The need to conserve energy must start with each of us as individuals. The market can only function efficiently if we exercise our perogative within the system and demand building materials, technologies and systems that promote green building objectives and conserve energy.

Only 52% of windows used in new construction have windows that maximize energy conservation beacuse builders and consumers are unaware of the technologies that are available or fear that they are too costly. Some are, but glass technology has come a long way over the last 30 years and the cost of making energy efficient windows has come way down as the technologies have gained ground. There are also now rating systems and standardized tests developed by independent private associations and governmental agencies to guide the Architect, Builder and Consumer in selecting the window that will perform the best for the given locale you are building in.

Chief among these are the Energy Star Qualified products registry and the National Fenestration Rating Council. Energy Star ratings are supported and maintained by The U.S. Department of Energy. The NFRC registry is maintained by an non-profit industry organization that mandates testing protocols standards and designates independent labs to certify the performance of the windows of the participating manufacturers and Consumers and Building professionals can visit the sites to learn the specific attributes of a glazing system are most desirable for their location (what Zone they a are living in) so they can select a window that has been designed and engineered to best attain the desired levels of performance for their zone.

Each Energy Star Zone has specific minimum U-Values and Solar Heat Gain Co-efficients (SHGC) that they must meet in order to be listed as "Energy Star Qualified". There are also suggestions for specific optimum perfromance criteria there so that an individual can select windows that exceed the minimums and select the best combination of attributes for the windows in their home.

In general, those living in the Southern zones need to be more focused on SHGC measures because in these zones, cooling loads use the bulk of energy to regulate the homes temperature inside. In the Northern zones, U-Value is more important because heating uses more energy for keeping the home comfortable. If you live in Miami, it is more critical that you reduce the amount of heat gain coming through the glass and if you live in Detroit, it is more important to reduce the amount of heat loss through the glass. Fine tuning the glazing is important and can lead to reductions in heating or cooling costs of up to 30%.

Now most builders will choose the least expensive window they can to hold the price of the house down. It is up to the end consumer and local building codes to begin to consider life-cycle cost instead of initial cost in designating window performance levels. New technologies that make windows optimally efficient can be had for and average cost as low as $ 15.00 per window (source: Cardinal Industries, Inc.). The payback for a cost like this is less than a few years and has become very easy to consider given the rise in energy costs over the last few years.

So learn for yourself. Go to Energy Star Zones or Efficient Window Collaborative to learn what is the best combination of attributes and find a window that is best for your home.