Glossary of Energy Rating and Building Terms

AFUE	EF
HERS	WHOLE-HOUSE SYSTEM
IECC	INFILTRATION
R-VALUE	SEER
U-VALUE	ADVANCED GLOSSARIES

AFUE - Annual Fuel Utilization Efficiency - A measurement of the efficiency of the heating equipment, determined in laboratory conditions. It does not take into account the distribution system (ductwork).

EF - Energy Factor - The measurement of the overall efficiency of a water heater. It is the fraction of the usable energy compared to the energy put into the water.

HERS - Home Energy Rating System - A system through which energy ratings are performed. Standards are set and governed by RESNET www.natresnet.org (Residential Energy Services Network). Systems are operated by HERS Providers, which ensure quality control and customer service.

WHOLE-HOUSE SYSTEM - House as a System / Whole-House Approach / Systems Thinking - Equivalent phrases that describe an approach to home building which more strongly integrates the subcontractor into the design and construction process and considers the impact that any change to one system in the home has on other systems. These processes are the foundation of high-performance building.

IECC - The International Energy Conservation Code - An energy conservation code which is compatible with the International Codes. The IECC is usually adopted along with the adoption of the International Residential Codes (IRC). Chapter 11 of the IRC includes the IECC. Within the IECC, Chapter 4 is the chapter that defines the performance path to comply with the code. This covers energy ratings provided by energy raters.

INFILTRATION - The amount of air leakage into and out of the home - The air in must equal the air out. This is measured by a blower door test which reports the cubic feet per minute (CFM) measured during the test.

R-VALUE - The measure of a material's resistance to heat flow - The higher the R-value the better. The term is used for insulation products, such as insulated sheathing, batt insulation and blown insulation.

SEER - Seasonal Energy Efficiency Ratio - The measure of efficiency for a central air conditioner. This is the amount of cooling capacity divided by the energy it uses.

U-VALUE - The inverse of R-value - The lower the number the better. This term is used to describe windows and doors. For a comprehensive glossary of window terminology, click here.

ADVANCED GLOSSARIES

Building Science

Windows