Volume 48, Issue 6 - November/December 2009
Southern Hurricane Zone:
A Unique Market Offer Sound Recommendations
When Selling Energy and Impact-Resistant Benefits
As a fenestration dealer you owe it to your customers to understand
the costs and benefits of energy savings in southern markets.
There are a host of agencies and governmental bodies stimulating our energy needs these days. Some provide their recommendations adjusted for zones such as Energy Star®, some offer stimulus rebates based on somewhat arbitrary performance values like the .30/.30 tax rebate program (for an update on .30/.30 see article on page 8), many states have defined energy requirements for buildings and many rely on the LEED program, which awards points based on a variety of advantages from energy savings to product recyclability. None take into consideration both the importance of favorable energy attributes combined with the security and wind-borne debris resistant capabilities needed in hurricane-borne regions.
Window dealers should be able to offer sound recommendations when giving advice to consumers choosing doors and windows. Lets try and clear up some of the myths.
Hurricane Impact Requirements
Markets and applications requiring hurricane impact product protection vary based on building codes and building and consumer requirements. For markets in hurricane zones, there are a number of products that provide wind-borne debris protection as well as various levels of energy efficiency. It is in these markets that one must not only shop for energy-appealing products but provide for adequate protection for their homes or buildings, their safety and contents.
Even with the array of available impact products on the market and certain localities having long established and formidable building protection codes in place we still have an inconsistent set of regulations throughout all of our countrys hurricane prone regions. Inconsistency in building codes by state arguably may not be preparing localities adequately against the potential billions of dollars in cleanup and repair bills that are ultimately paid by citizens through their own losses, through insurance coverage and governmental support. This inconsistency means that ultimately the right decision rests on the shoulders of the building owner to make good hurricane protection choices.
Not all impact products are alike or offer the same level of protection just as not all products offer the same level of energy efficiency. In the case of hurricane-resistant products, we hear a lot about impact glass but having this protection provides only part of the answer. A products overall framing design, hardware and installation parameters all must be taken into consideration. Strong framing, large glass bit, secure hardware and properly defined installation and anchoring techniques tested with reputable third-party engineers should all be considered.
The Use of Insulating Glass
Say you are a dealer of impact products in Jacksonville, Fla., and a customer wants the most energy-efficient impact window on the market. You direct your customer to the latest insulating laminated window available. He is going to save lots of money on energy, right?
In large part, insulating glass (IG) is designed to keep heat inside. Its effectiveness is optimal in colder northern climates where maximum temperature differentials between inside and outside occur over a number of months. When facing a decision as to whether or not to use IG products in southern climates it is important to understand the true energy savings that will be achieved versus the additional cost you are adding to your purchase. As with most investment decisions you should calculate the payback to be received on an investment using the IG product option.
Considering locations within the hurricane region, the chart below reflects both average monthly temperature and outside versus inside temperature differences for three met ropolitan areas in Florida.
Given that the average temperature ranges in these climates are not dramatically different the resultant energy savings potential provided by insulating glass and U-factor efficiency is less. In southern climates these factors are not key drivers to major energy savings as compared to what might be gained in northern regions. Because of this fact, it makes financial sense to analyze the payback achieved by comparing the savings achieved in your energy bill against the added cost of IG to determine just how long it will take to offset the additional product cost.
For those who are looking at overall energy consumption over the entire process, does it make sense to consume energy to provide an IG unit that is heavier, more costly to ship and more costly to produce if it does not provide a significant energy benefit?
The Importance of U-Factor
Most define energy performance in fenestration products by measuring solar heat gain coefficient (SHGC) and thermal transmittance (U-factor) values, which determine how well a system blocks heat caused by sunlight from entering and how well a system prevents heat from escaping.
The U-factor or thermal transmittance value depicts how well a system prevents heat from escaping. In the case of northern climates this efficiency measure is important to saving energy. In southern climates, however, the difference between a superior and an average U-factor does little to help the overall products energy efficiency because the inside versus outside temperature differences are much less.
Let us look at the energy saving impact a change in the U-factor will have in Miami and Jacksonville. Our example (using a range from 0.30 to 1.00) shows the annual savings in energy consumption between these two efficiency levels. In Miami, there is a negative impact as actual energy costs increase by $23 where in Jacksonville the annual savings within this range is $124.
It is important to point out that in southern climates, the cost necessary to achieve a dramatic improvement in thermal transmittance (U-factor) far outweighs the benefit obtained in energy savings. A payback analysis will not be favorable by any stretch.
The Importance of SHGC
The solar height gain coefficient (SHGC) value depicts how well a system blocks heat caused by sunlight from entering a building. In this case, the energy efficiency gains received in southern climates from superior SHGC values are more relevant. Keeping the extreme temperatures of an afternoon sun from penetrating through a window opening reduces the air conditioning load of a building. Of course in addition to window products, exterior awnings, trees, building overhangs and window facings all help to reduce this infiltration and should be considered as well.
In the example, again for Miami and Jacksonville, you can see that an improvement in SHGC between the range of 0.3 and 0.8 provides a greater savings in energy usage to that of U-factor. In Miami, the annual savings is $324 and in Jacksonville $215.
There are various ways to improve a fenestration products SHGC performance, which, for the most part, revolve around glass type. The predominant approach is to use tinted glass or low-E coated glass. Again, the cost benefit payback analysis should be performed on these alternatives so that you are paying for energy savings wisely.
Energy Saving Options and Payback
Let us now understand the costs and energy savings generated by simulating various impact glass configurations for homes located in Jacksonville and Miami. The example assumes a 4,400-square-foot home with 700 square feet (16 percent) of window openings. The energy calculations are performed using RESFEN software from the Environmental Energy Technologies Department Lawrence Berkeley National Laboratory managed by the University of California.
For the purposes of this example we have assumed typical costs for an installed hurricane impact window package and energy costs for this type of home. Obviously these amounts will vary somewhat depending on the quality of window package chosen, local utility rates and the homes exposure to the elements. You can see from the example that options providing improved SHGC and U-factors can save energy but at various years of payback. In Jacksonville, paying $10,000 for insulating glass with LoE 366 will only save you another $30 per year when compared to a laminated LoE 366 option.
have to decide what is more important, protecting
their homes sizeable investments and their contents from a hurricane or saving a
couple of hundred dollars annually in the electric bill. The trends in energy standards and codes today do not seem to balance these two needs appropriately."
When selecting hurricane-resistant doors and windows you will want to consider both their energy-saving features as well as their ability to protect and to last. Not all impact-resistant products are made alike nor will all energy-saving options provide your customers with an acceptable return on investment. Consider laminated glass with tinting or low-E coatings for the southern climates. Get educated, and educate your customers, too. Try out the RESFEN software at http://windows.lbl.gov/
software/resfen/resfen.html to better understand the real benefits of insulating glass in southern climates.
Consider your local building codes and requirements for impact products. Many codes today may not require the right level of protection for you against major hurricanes so do your homework and, when in doubt, install products that exceed the locally recommended levels of protection, particularly if you live in areas where protection guidelines have not been fully developed.
When advising your customers, balance the need for superior impact resistance against the cost of energy efficiency. Your customer may instead decide to spend their IG savings on better insulation and higher SEER rated air conditioning.
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