Energy Efficient Building

Energy efficient building is becoming more important as fuel costs rise people become more energy conscious. Homeowners and owner builders are looking for ways to construct a better performing and more efficient home.

House as a System

Experts in the residential construction industry have been researching energy efficient building and house performance for decades. The building sciences have determined that an individual component's performance is heavily dependent upon building the whole house as a system. If one component is weak, the overall system performance is less.

For example, if there are gaps and voids in the insulation, the air conditioner or furnace will have to use more energy to meet thermostat requirements. If the house is well sealed but there is no fresh air ventilation, the home may become humid and air quality will suffer. This is a mistake that many well-intentioned builders make. CONTROLLED fresh air ventilation is critical to energy efficient building.

Insulation

A well insulated building envelope is an essential portion of the energy efficient home. That means insulation should be properly installed without gaps or voids. A gap in insulation results in convection ( hot or cold air moving through the wall cavity). If air movement is allowed, the walls temperature will rise or fall with that movement, eliminating the insulation value of the wall. Any void in insulation can cause inbalance in the house and will result in cold spots or hot spots in the home. The type of insulation used can impact the ease of installation AND the overall performance of your insulation assembly.

Windows

The owner builder should consider the type of windows that will be installed very carefully. Low-E (low emmissivity) windows reduce solar heat gain in the summertime. Double pane and triple pane glass with argon slow heat transfer. This can help lower the work load of the home's air conditioning system.

In northern regions, it is necessary to weigh the benefits of solar heat gain warming the house part of the year. Manufacturers have improved their glass in many cases and have designed specifications for different climates.

It is important to also consider the heat transfer that occurs when using metal framed windows. If energy efficient building is the goal, vinyl windows are a better choice. Metal framed windows transfer heat from the outside. The same thing happens if steel studs are used for exterior walls. Vinyl frames now are very strong, multi-chambered, and engineered. Options exist for insulated chambers and factory paint of some products. Many career a lifetime guarantee.

While windows, even in recent years, have been referred to as "a hole in the house," today windows are made that actually carry an R-5 insulation value. This is still less than a standard insulated wall but it is leaps and bounds better than the past.

Another method to reduce heat gain and loss are insulated window blinds placed in front of each window. This method allows for the buyer to address energy efficiency even if the windows on the home are already installed. Rather than investing thousands for removal and refit of windows, a homeowner may purchase insulated blinds. An added benefit to window blinds is the color variety and style range that blinds offer. The right windows are a key component to an energy efficient building.

Tight House

A tight house is a well sealed house. This house does not allow UNCONTROLLED air infiltration. Air infiltration allows climatized air to escape and exterior air to come in and impact the interior temperature. The forced air unit will be working much harder to compensate. This additional work makes the home less energy efficient and leads to unecessary higher heating and cooling bills.

Fresh Air Ventilation

Energy efficient building and the whole house system call for a tight house. To prevent the stagnation of air and accumulation of moisture inside, fresh air ventilation should be employed. Fresh air systems control the intake of fresh air and the removal of interior air.

Blower Door Testing

A blower door test is employed to test the tightness of a house. The air exchange rate is gauged by putting the house under pressure. This will expose any leaks in the home. The owner builder can then locate the leaks and seal them.

It costs around $200.00 to schedule a blower door test. Ask the testing contractor if there is a combination price for both the blower door test and the duct blaster test. Find out what is included. Inquire if the test includes locating leaks and minor sealing.

Sealed Ducts

Many homeowners do not realize that the performance of their forced air units is compromised. They have leaks in their ductwork or registers. It contributes greatly to the overall efficiency of the home to seal all ducts and registers. Registers can be sealed by applying mastic to all the seams. Sealing prevents air loss into the attic space or crawlspace.

Duct Blaster Testing

Duct blaster testing will indicate how much leakage is present in the A/C ducts. The contractor that does the blower door test will normally conduct the duct blaster test at the same time.

A blower is attached to the house ductwork and registers are sealed. The testing company has very sensitive instruments to measure air pressure and can determine how much air is lost into the attic via unsealed ducts.

While I was a superintendent at Pulte homes, energy efficiency was a top priority. We tested each house or living unit(condominium) we built for tightness. I once had a unit under construction that continued to fail the test. Finally it was determined that air was escaping at the edges of the register attached to the testing gear. Once the register had been properly sealed with mastic, we passed the test successfully. Insist on sealed ductwork and mastic on of all the registers in the house. This will likely be an up charge for most HVAC contractors unless negotiated into the contract on the front end.

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