Insulation’s Thermal Resistance Value (R-value) refers to a fiber or coating’s resistance to heat flow (penetration or loss). The great thing about insulation and weather-stripping is that it works in both hot and cold weather. When it’s cold outside, insulation helps prevent heat from flowing out of the house and when it’s broiling in the summer, it helps prevent heat transfer into your home. Choosing R-values that are right for both the location in your home and the geographic climate in your region are key.

The U-Factor measures how well a window or wall prevents heat from escaping. It measures the rate of heat transfer through a building element over a given area, under standardized conditions.

The biggest difference between U-factor and R-value is that U-factor measures the rate of heat transfer (or loss) and R-value measures resistance to heat loss. These measures are applied to multiple building materials.

Solar Heat Gain Coefficient (SHGC) measures how well the window blocks heat caused by sunlight. SHGC is measured on a scale from 0 to 1. The lower the SGHC, the better the window or window coating will block unwanted heat. Low-Emissivity (Low-E) films can be applied to existing window interiors to lower high SHGCs and keep you cooler in summer months.

In the Northeast, according to the US EPA's ENERGY STAR Qualification Criteria, ideal measures for new residential windows would be as follows SHGC: ≥ 0.40 to ≥ 0.35, U-factor: =0.32 to ≤ 0.30. Ideal measures for Glazings or Low-E films would be - SHGC: ≤ 0.30 (> 1/2 lite or ≤ 1/2 lite), no rating (for opaque); U-factor: ≤ 0.32 (> 1/2 lite), ≤ 0.27 (≤ 1/2 lite), ≤ 0.21 (for opaque). [hide]

The US EPA’s energy performance rating system. Devices carrying the ENERGY STAR® logo, such as computer products and peripherals, kitchen appliances, buildings and other products, are designed to use 10%-50% less energy and water than standard appliances and save an average of 30% over standard models. Federal ENERGY STAR®-rated appliances are designed to use 10-50% less energy than regular appliances.

Like Energy Star, Seasonal Energy Efficiency Ratings (SEERs & EERs) are measures of efficiency (think savings) but both are specific to energy used in air cooling or how many BTUs per hour are used for each watt of power drawn - SEER for central AC and EER for window-mount or room AC. Top cooling units have SEER/EER ratings as high as 19. Older central air systems, or cheap new window-mounts, have SEER/EER ratings of half that. You can save up to 50% or more on your cooling bill by replacing an outdated AC unit with one that has a high SEER/EER rating: Start at a minimum of 14 or better. Additional considerations include your average AC use each summer and the utility rate per kilowatt-hour (kWh) you pay.

For heating, Annual Fuel Utilization Efficiency (AFUE) percentage is the most widely used measure - It is a season-long average of the thermal efficiency per piece of equipment that calculates heat actually delivered to your house compared to the amount of fuel supplied to the furnace, boiler or water heater. The higher the AFUE percentage, the more fuel your unit is converting to actual heat for use inside your home and the higher your return on investment.

If your furnace or boiler is 10-20 years old, you and your Para Contracting home performance auditor can best evaluate whether to replace the unit with a better performer or whether better insulation and air-tightness will be the most energy- and cost-effective approach.

If your water heater is 15-20 years old, it’s gotta go. You may have heard about several new options available:

Tankless Water Heaters provide hot water on demand at a preset temperature which reduces or eliminates standby losses and yields savings up to 20% for electric models.

Indirect Water Heaters remains one of the best options because they eliminate significant flue losses associated with gas-fired storage water heaters but without the hassles and extra costs of tankless gas water heaters. They use your boiler as the heat source by circulating hot water from the boiler through a heat exchanger in a well-insulated water heater tank. Indirect water heaters are particularly good for boilers and provide multiple savings benefits:

• High Efficiency
• Rebates when installed with newer, high efficiency gas boilers
• Ideal for use with Solar Thermal Systems for even higher savings & a lower Carbon Footprint

Between gas savings ($50-$100/yr) and reduced CO2 emissions - these energy savings are hard to beat.