10 Steps To Ensure Maximum Comfort and Energy Savings
Building a home with spray foam insulation is a great start, but there is more you can do to realize maximum energy efficiency. The true secret to optimum energy efficiency is to make the structure as air-tight as possible while keeping the air quality very pure to ensure a healthy, mold-free environment. To do this, EnergyWise uses a proprietary computer program that was generated from experience derived from NASA thermal consultants for the Mercury, Gemini and Apollo space programs. This software has been upgraded and fine tuned after more than 25 years of experience in analyzing thousands of structures.
Key Step 1: EnergyWise expertise in correctly sizing and producing an accurate mechanical layout of the HVAC system.
HVAC contractors often think more is better. It isn't... even for heating. Correct sizing of HVAC units is critically important to the overall efficiency and performance of the system. Unfortunately, most people do not realize that the delivery of the appropriate quantity of air is as equally important, perhaps even more so. There are hundreds of ways to install a duct system incorrectly and only a few ways to properly install it. This is an area that is often overlooked and taken for granted, until a customer does not have adequate air flow or has hot and cold spots in their home. By then, it is often too late to correct the problem.
Key Step 2. Install high-quality windows and doors.
When you are sizing mechanical systems for ICF structures, the load required largely depends on the windows and doors: how many, how well insulated they are, and what direction they face. EnergyWise recommends using "thermally broken" windows, those with wood, fiberglass or vinyl frames as opposed to aluminum, which readily conducts heat and cold. Using double-pane low-e glass in windows and doors will also curtail heat loss in the winter and heat gain in the summer. Look for the U-value of the total window unit, not just on the glass -- anything below 0.35 is good. The U-value measures the conduction, radiation, and convective heat transfer from the warm side to the cold side of the window. The lower the U-value, the better insulated the window.
Key Step 3. Control interior moisture.
In air-tight homes, it is essential to control humidity levels to prevent mold and mildew problems. It is very important to address every room in the house that creates moisture, such as the kitchen, laundry room, and bathrooms. Rememdies include installing humidistatically controlled fans in the bathroom, installing fresh-air venting in gas fireplaces to prevent drawing combustion air from inside the house, and avoiding kitchen vent hoods that simply recirculate humid air.
Key Step 4. Caulk every spot where air could enter.
The rule of thumb: If it looks like it could leak air, caulk it. You cannot overcaulk. Pay special attention to windows and doors, caulking them thoroughly with an acrylic siliconized material. On the interior, he says to caulk any penetrations into the attic or crawl space.
Key Step 5. Use variable-speed HVAC equipment.
A single-speed furnace and air-conditioner consistently comes on full-blast no matter what, which may be okay in the dead of winter or heat of summer. However, in the spring and fall, or when outdoor air temperatures are less extreme, a single-speed unit may heat or cool rooms too quickly. Variable-speed equipment can ramp down from a 5-ton unit, for example, to as little as 2 tons. This will help control moisture in a foam insulated house much better because the unit will operate at a lower speed and run longer to control humidity. To assist, a humidistat that works in conjunction with the thermostat will continue to run until the house reaches optimum humidity levels. As a result, not only will you have an ultra energy-efficient home, you will also have a healthy home with dramatically better air quality. Keeping humidity levels below 50 percent creates an environment where even dust mites and mold spores can not survive.
Key Step 6. Insulate the attic with sprayed polyurethane foam.
Sprayed polyurethane foam, applied to the underside of the roof with no attic venting, will keep the temperature of the attic within 6 to 10 degrees of the temperature of the living space year-round.
Key Step 7. Locate all ductwork in insulated space.
Ironically, the ducts that distribute conditioned air throughout the home are often the most poorly insulated elements of the thermal envelope. Adjustments in construction that locate the ductwork in insulated space will be rewarded with a sizeable reduction in monthly heating and cooling bills, and sometimes a drop in HVAC system requirements.
Key Step 8. Avoid the use of recessed can lights.
Recessed lights that penetrate into the attic space can be a nightmare unless you have insulated the attic with sprayed foam. One of these seemingly innocuous little lights represents one square foot of uninsulated attic space, and 20 of them is equivalent to having a door open in the attic at all times. When a homeowner insists on recessed lights, he recommends paying a few extra dollars for double-walled, insulated, air-tight can lights with air-tight seals.
Key Step 9. Install compatible HVAC systems.
Only use HVAC equipment from the same manufacturer to optimize operating efficiency. HVAC contractors are notorious for mixing and matching equipment to save money, but the system will run more efficiently if all the components including the condensers, furnace and coils are from the same manufacturer.
Key Step 10. Provide "ventilation on demand."
Homeowners with foam insulation are sometimes concerned that their homes are too air-tight and will permit the buildup of dangerous carbon monoxide levels. For peace of mind, install a "ventilation on demand" system (a CO2 sensor) that automatically monitors and corrects the air quality of the home. Ventilation on demand also eliminates the need for a separate system to continually bring in outside air, which often polluted and humid.
