Guaranteeing a comfortable home is not a fantasy. This article explains how to go about designing a home to ensure satisfaction.
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California builder D.R. Horton explains how there can be no more than a 3-degree variance between rooms of a house — no cold spots and no drafts. Plus, builders scientifically estimate the amount of money it will cost to heat and cool the house and "guarantee" the bills will not exceed that amount. This is done by taking an "integrated" approach to home building. They analyze items such as wall depths for insulation, ceiling heights and thickness, window efficiency, furnace efficiency, spot ventilation and other criteria. They are so sure of their estimate that they'll reimburse a homebuyer if the utility bill goes over the estimate.
"My old house had 20' ceilings and it was constantly cold in there," said Wesley Herman, who purchased a D. R. Horton production home in Sacramento, Calif. "It was just not a controlled environment at all — whether it was coming in through the doors or around the windows." Rhonda Fox adds, "D. R. Horton guarantees the comfort of the home, and the way that they've done that is by doing some extra caulking around the windows, the framework. The doors are insulated so when you come in from the garage it's a very solid door, a very solid seam."
The ductwork and extra insulation are cost efficient and the temperature from room to room in the two-story home never fluctuates more than 3 degrees, which is part of the comfort-guarantee agreement.
"One of the features we enjoyed is the fact that there is guarantee for the comfort," Wesley said. Rich Coyle, purchasing director for D. R. Horton, said, "Not only does the house have to perform; they [Wesley and Rhonda] have to be comfortable within that house. But we want it to be energy efficient ... comfort is key."
In order for D.R. Horton to offer this guarantee, they have to run a lot of tests, which start when the plans are drawn up. "The houses are put through a series of plan checks so that we can model how the house is going to perform under ideal conditions if we take care and do the various things that we need to do," Coyle explains.
The focus for the builder is to "integrate" the home's elements to work together, making the house more comfortable and efficient. They determine the size of the heating and cooling system, taking into account the following:
Size of the house
Type of insulation
With the heating, ventilation and air conditioning (HVAC), they are trying to make the most efficient system possible in the house. The key is not to oversize the HVAC equipment because it could short-cycle. For example, a five-ton unit may be way oversized and come on for a short time, throw a bunch of cooling in the house and then shut off. A four-ton unit may perform much better, which means it would run longer but will be cheaper overall due to the energy efficiency. There also will be less stress on the equipment because it fits the needs of the house perfectly.
But if the home is not built "tight," which means the house envelope is wrapped properly, the size of the HVAC system won't matter. This means better windows.
Low-e Windows (Web extra)
The biggest news in window technology is "Low-e" windows, which stands for low-emissivity. Low-e glass for windows means that the windows are made of a special high-performance glass and coated with a film that allows the shortwave radiation of solar energy to pass in, but block most of the long-wave thermal energy trying to get back out.
The characteristics of Low-e glass or films are geared toward energy saving and can do several things for your home. Low-e films block most solar heat gain while transmitting the most visible light. Windows treated with Low-e film help in both the winter and summer, with little heat leakage coming inside on a hot summer day, or leaking outside in winter, which reduces the homes AC load.
In many cases summer cooling costs can be greatly reduced due to the lower solar heat gain. Since Low-e windows have a low solar heat gain coefficients (SHGC), the shading co-efficient is better for helping keep harmful heat and UV rays out of the home. SHGC measures how well a product blocks heat caused by sunlight. The SHGC is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed, then subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits.
A Low-e coating is virtually invisible from the inside, but most brands tend to give windows a semi-mirror appearance from the outside. Low-e windows are available ready-made from the factory, where the thin plastic film with the metal coating is suspended between the glass panes, or, Low-e films can be applied to existing windows.
This type of glass is available from most window manufacturers. Consult your contractor to find out which type of window is best for your home.
Another part of creating comfort is making sure the walls are keeping the house as warm as possible, which means the insulation should have a high R-factor. This is a resistance to air flow and heat, which means the insulation is "slowing the cold from coming into the house."
Blown-in fiberglass insulation will fill the wall cavity completely and has a high "R" value/factor. The more R-value in the wall insulation means there will be more resistance to heat and cold and the better it will perform.
With tighter construction, low-e windows and better insulation, it's important to have an air-cycler to bring in fresh air. A 6" duct runs to the exterior of the house and will come in via the air-cycler into the cold-air return and is distributed throughout the house. Even though the HVAC unit is not heating or cooling during this process, it will still run quietly on timed intervals to provide constant fresh air.
Note: If the comfort guarantee can't be met — if the rooms are more than 3 degrees off or if the utility bill exceeds what D. R. Horton predicts, the homeowner will be reimbursed and the problem will be fixed free of charge.