When Windows are an Appropriate Selection

With the onset of energy-conscious consumerism, there has in turn been the creation of energy-oriented marketing campaigns. One of the most prominent campaigns has been those of window manufacturers and installers, with most of these campaigns focusing on window replacements. There have been varied opinions on whether the replacement of windows is warranted. Ultimately, the numbers prove that unless your windows are extremely leaky or in disrepair the replacement of windows has an extremely long payback. This extended payback makes window replacement one of the last items on a proper energy conservation list of improvements.

However, window installation in new homes takes on a different perspective. Due to windows playing a large part in the energy consumption in a home, they are one of the most important factors to consider when building a home. This may seem counter to the above perspective, but one must consider that when building a new home, one must install windows. The additional cost for improved and more energy-efficient windows are minimal compared to the amount of savings they will produce.

In new energy-efficient construction, window selection should be considered just as important as selecting your HVAC system or site layout. For that reason, it is important for you to understand the different types of windows available.

While there are many different types of windows, and their structure affects how they function, there are basic components common to each one. Besides the type of window, to make a wise decision in selecting windows, one must understand the basic components of a window. These are the frame, glass, spacer (for multiple pane windows), coatings, and gas fill.

Frames
Wood
Vinyl
Aluminum
Glazing
Coatings
Gas Fill
Spacers



Frames
The frame is the material around the glass, and essentially makes the window. The frames can be made from various materials, and the frame material affects the amount of heat the unit can conduct around the glass. There are several different types of frames and they range greatly in price.

Wood
Wood frames have long been considered a sign of quality and performance. There are some issues with wood frames, such as the susceptibility to rot. This has been improved by cladding the exterior with aluminum or vinyl. Overall wood frames are a good selection, especially with the cladding. The U-Factor of the frame is around 0.3 to 0.5. (The lower the U-Factor, the better, when selecting a window)

Vinyl
Vinyl has been a mainstay for cost conscious builders and for this reason come in a wide range of quality. Vinyl is similar in U-Factor as wood and does not have the problem with rotting. However, vinyl does expand and contract greatly, affecting the leakiness of the window; in lower-quality windows, vinyl can degrade with exposure to UV light.

Fiberglass
These frames are stable and energy efficient. The frames can even be filled with foam to increase the efficiency. The U-Factor of fiberglass frames range between 0.2 and 0.3.

Aluminum
 Avoid them! While aluminum windows are available, they should be avoided for new construction.

Glazing
Glazing is simply the glass in the window. Glazing can be found in single, double, or even triple pane. Each additional layer of glass increases the efficiency of the window. To truly take advantage of the window panes, the spacing between panes needs to be at least ½ “.

b>Coatings
The most common coating is Low-E. This works by reducing the amount of infrared energy that enters the home. The coating reflects the energy away from the home. Additional improvements can be made to the coatings by using Heat Mirror technology. This is film adds additional surfaces for Low-E coatings and creates the effect of triple glazing. 

Gas Fill
Gas fill helps reduce the convection heat transfer in the glass. The temperature difference on the glass can create convective flow within the panes of glass. This movement of air and transfer of heat can minimize the benefits of multiple pane glass. By adding heavy gas into the spaces the potential for convective loops are reduced.

Spacers
Spacers are what separate the panes of glass and are often overlooked. There is little that needs to be known about spacers other than when possible select a spacer that has a lower conductivity.

The better the combination of these components the more efficient windows will be. There are even windows being developed that will have R-values close to those of the walls they are placed in.

Install your windows correctly!
There is more to installing windows than just setting the unit into the opening. One must properly seal, flash, and set the window. When installing a window, ensure that you have the window properly set into the opening, the window and opening is flashed to prevent water intrusion, the building wrap is properly installed around the window, and the gap between the window and the rough opening is properly insulated. Having an efficient window does you no good if it is poorly installed!

Why HVAC Isn’t Just a Lot of Hot Air (or Cold, Either)

Ever since I started my career in the construction industry, I have always seemed to run into problems with HVAC systems. This shouldn’t be that surprising, since the HVAC system is the primary system responsible for the living conditions in your home and can have the most impact on how a building functions. I have seen systems that are contaminated with fungal growth, systems that you would think had been installed to provide irrigation to the crawlspace, systems that my 8 -year-old niece and nephew could have installed, and systems that are a piece of art. However, out of all of these, the latter is the rarest of them all.

In the past year, I have dealt with systems that

• increased the gas bill after the system was installed,
  
• caused the homeowner to pay more per month than they were per season before it was installed,
  
• were not cooling or heating the home equally. The excuse for this was that two systems should have been installed, when the contractor installed only one - however, that one unit was not properly installed (twice), and ended up causing damage to the ductwork.
  

These are only three of the multitude of cases where I have seen of improperly sized, installed, or designed units. Why is this? The only explanation I can come up with is that homeowners - and unfortunately, most HVAC technicians - do not understand the impact the system can have on the home, and that it is not as simple as a fan moving air through some round tubes.

There is a standard of practice set forth in both the building code and by industry organizations that state how a system should be designed. This process takes into account how each component of the system works with the other, and combines them to provide efficient delivery of your conditioned air. This whole process starts with what is called a load calculation, or Manual J calculation. This takes into account the construction of your home and how heat is transferred between the exterior walls, ceiling, floor and the exterior environment. The next step covers the system selection or Manual S. This outlines the proper method to select a system to accommodate for the required load calculations. Next comes Manual D, which is another critical step as this is the duct design. Each system must have the ducts designed for the unit to be installed. Finally is Manual T, which is the register and grill sizing. Even grill sizes can impact your comfort levels!

Properly designed systems can increase your comfort and decrease the cost of your utilities. Next time you are going to have your HVAC system replaced, take note of these simple reminders, and hopefully, you will have your system properly installed:

1. Make sure Manual J, S, T, and D calculations were performed for your system.
Of all of these, Manual J and D are the most critical. Whether you are having your home system replaced (ducts and system) or just the unit, these calculations are critical. There is no such thing as rules of thumb or matching the system with what you previously had. Each home is unique, and the system you had before may have been improperly sized.

2. Your ducts impact your system’s efficiency.
While most people will try to just install a new unit and keep using the old duct work, this can actually cost you money. If ducts are improperly sized for the system, they can cause the system to operate inefficiently. Why pay for the more efficient system if it is going to operate at a lower efficiency than the one you just replaced?

3. Manual J has safety factors already figured in.
There are some companies that will perform Manual J calculations, but they will not use the weather data provided in the back. Instead, they will design the system for hotter temperatures. You don't design systems for newsworthy days! By raising the design temperature, you oversize the system. When you do this, you size the system for 1% of time it is in operation - and oversizing for 99% of the time.

4. The lowest or highest price may not be the best.
It's hard to judge an install on just the price of the system. HVAC installs can vary greatly! ACCA (Air Conditioning Contractors of America) has produced a document that allows you to compare bids so that you get the best value. However, remember that if the contractor doesn’t properly design the system, it doesn’t matter how good their price is! You can get the document here: Quality Installation Specifications

Do NOT Install Replacement Windows!

The tip this week is more of a what not to do instead of a what to do. Every day, I see a commercial advertising replacement windows and how much money they can save you; and every day, I know someone has invested a lot of money into their home that they will not get paid back.

Many people are advertising 50% savings with the replacement of new windows. This is completely true. You may save 50% on the amount of energy the windows cost you, but this translates to only about 10% to 15% of your total bill. With this limited savings as compared to the cost of the windows, you end up with a very long payback period. If 10 windows cost you between $6000 and $7000 and you save a gratuitous 20% on a utility bill of $200, your payback will be between 12 and 15 years. This is almost a best-case scenario. In most cases, the paybacks for replacement windows are going to be between 20 and 30 years, because the savings will not be that great for such a small investment.

Most homeowners are not going to be in the home for 15 years, and if they are, there are several other items that can be done to the home that have a quicker payback. I will only recommend replacement windows in extreme cases. In the majority of the homes I see, I would more likely recommend installation of storm windows (for single panes), or repair of the windows currently in place, typically because those are the best scenarios when windows are involved. So next time you have someone suggest you replace your windows or you see the commercials, remember that those windows will save you money, you are better off investing in other, similarly effective improvements that have a much shorter payback period.