Greentech Construction

Our most important consideration

It guides every step of our thinking from initial planning to project completion. We design and build our homes to consume as little energy as possible.Most people assume that their homes have insulation and building codes to enforce those standards. That much is true. But it represents the minimum level of insulation that is acceptable, so that if you are told by a builder that he insulates “to code”, know that it is the bare minimum below which is a violation.That bar is set very low. We can and should be building homes that use 50% less energy than the current building codes require.

The Building Envelope
30-50% of a typical home’s conditioned (heated or cooled) air is currently lost through leaks in the Building Envelope: its floors, walls, windows, doors, ceilings. It is the barrier between conditioned and unconditioned space.The vast majority of Ohio’s current housing stock was built with 2×4 stud walls stuffed with fiberglass insulation which is often poorly installed and does not stop air infiltration. (Think of the fiberglass air filter in your furnace). All of those seemingly tiny holes, cracks and gaps add up to essentially create a hole in the wall. In some homes it’s the equivalent of having a window wide open in the dead of winter.

Build it Tight, Ventilate it Right
Properly designing and building a super-insulated and tight Building Envelope is critical to achieving a green energy saving high-performance home. Time spent here adds lasting comfort and value to your home and yields dramatic long term savings. People make a mistake when they focus all of their attention on all of the stuff (floor coverings, furniture, curtains, countertops, appliances, etc.) that fills the inside of the home and that is easily and often replaced. They end up with a nice looking Energy Hog. Once the Building Envelope is sealed in from the outside with siding and the inside with drywall, they are stuck forever with a poorly insulated, leak prone, poor performing and ultimately expensive decision.We have been building with SIPS, structural insulated panel systems, since 1987 and feel they yield an extremely tight, strong, and energy efficient building envelope. The Structural Insulated Panel Association or SIPA, is a good source of further information on their benefits.

By exhausting air out of the house, we are able to test for and correct any air leaks in the building envelope. A thermal-imaging camera checks for cold spots.

Infrared photo of a poorly insulated home shows major heat leaks in the building envelope. Photo by T.Turner

Performance Testing
To be certain that the Building Envelope we build performs as designed, we hire independent Home Energy Raters, (Certified by the EPA’s Energy Star Program) who review the home’s plans, perform an energy analysis, assign a HERS Index score to it and perform inspections of the home.A house built to today’s building codes receives a HERS Index score of 100. Many older homes have very little insulation and when tested receive HERS scores of 200-300, meaning they burn 200-300% more energy than today’s “code built” homes. But to qualify as an Energy Star home, it must be 15% more efficient than today’s codes require, thus receiving a HERS Index of 85. A home with a HERS score of 50 should consume half the energy of the code built house. The lower the score the better, with the Department of Energy’s ZEH (Zero Energy Home) being the ultimate goal. With increasing concern about America’s rising energy costs officials around the country are working to make stronger building energy codes mandatory.

The Crucial Test
When we go to buy a new car, we instinctively check the window sticker to check the EPA’s estimated city and highway MPG rating. We research online and in magazines to learn which car, camera, TV, dishwasher, telephone, refrigerator or sunscreen performs best before a purchase. So why can’t we insist on applying a performance test on the most expensive purchase most of us will ever make in our lifetimes? We can and should.The equivalent to the automobile’s City and Highway MPG ratings window sticker for a home is called its HERS score. Approved home energy auditors can test your existing home as well as a new home. Sam Rashkin, head of the EPA’s Energy Star program has said that in the not too distant future you won’t be able to buy a home without knowing its HERS score.Once we feel we have a well designed and constructed home, it is time to put it to the test. Sometimes things look great on paper but don’t do well in the real world.

A thermal-imaging camera checks for cold spots.
The Blower Door Test
The third party Home Energy Rater uses the blower door equipment as a diagnostic tool to measure the air tightness of the home. All of the home’s doors and windows are first closed and the heating cooling system is turned off. Then a calibrated fan is installed, within an airtight frame, at a centrally located exterior door where it draws the air out of the house. Once a negative pressure has been established with the blower door’s fan, it is easy to check for air leaks in the building envelope as the home is drawing in outside air from every crack it can find to make up for the air that the fan is pulling out of the house. These leaks can easily add up to the equivalent of leaving a window open all year long. Some large leaks can easily be felt with the bare hand, others are found with a smoke stick or smoke pen while still others are discovered with a thermal imaging camera, which shows the temperature changes that leaks produce as different colors on its screen. All of this is done before the drywall goes up, when cracks can be sealed tight with caulk or expanding foam. The time to find leaks is before the drywall is applied as corrective action is much less expensive. A poorly insulated building envelope cannot hide from a thermal imaging camera. Think of it as a CAT scan or an MRI for your home.

Heating and Cooling

To help reduce those costs, whenever possible, choose geothermal systems to heat and cool the home as they are widely recognized as being the most efficient and environmentally friendly method. By using the constant 55 degree temperature of the earth, just a few feet below the surface, geothermal furnaces, through their ground loop piping, can deliver four units of the earth’s free energy for every one unit of electrical energy used. That translates into an efficiency of 400% when compared to the most efficient gas furnaces on the market, which rate 95%. The geothermal system also produces much of a home’s hot water needs. Homeowners can save from 40-60% on their total heating, cooling and hot water bills.