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Home Energy Audit to Evaluate Building Heat Loss or Heat Gain & Choose Heating or Cooling Improvements InspectAPedia®  -     Home Energy Audits help a building owner to Evaluate Building Heat Loss or Heat Gain & Choose Heating or Cooling Improvements How to measure or calculate heat loss (or gain) in a building How to measure heat transmission in materials: definition of R-values, U-values, K-values, BTU, calorie, and rates of heat loss or gain Building design temperatures & how to use a home energy audit or heat loss analysis What insulation "R" values should be used in a building insulation?

This article explains how to make best use of a home energy audit to reduce home heating or cooling costs. We provide related insulation and heat loss or heat gain analysis procedures including how to measure or calculate heat loss in a building, defines thermal terms like BTU and calorie, provides measures of heat transmission in materials, gives desired building insulation design data, and shows how to calculate the heat loss in a building with R values or U values.

Because no amount of insulation can keep a drafty building warm, also review ENERGY SAVINGS PRIORITIES. Also see HEAT LOSS INDICATORS (where is the building losing heat during the heating season, or gaining un-wanted heat during the cooling season), and see HEAT LOSS R U & K VALUE CALCULATION for a guide to calculating heat loss (or gain) rates for buildings and building insulation.

Formula-R™ and Owens Corning™ which may be visible in this photograph of pink Styrofoam™ insulation boards are registered trademarks of Owens Corning® and were photographed at a Home Depot® building supply center. © Copyright 2010 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Many people have heard of using "R" values to describe "how good" a building's insulation is. Here we discuss three measures of the flow of heat out of or into a building: R-values, K-values, and U-values. Each of these is defined below. But before moving on to these basic concepts of building heat loss (or gain) theory, it is essential that this still more basic point be considered:

It doesn't matter much how wonderful the building insulation is, how thick it is, or what the insulating material's "R" value is (see R defined below) if the building is leaky. If, for example, we're considering an older home with leaky windows or doors, or if we're considering a tall building with poorly controlled heat in winter, such that occupants of the upper floors are leaving windows open in winter then the heat flow out of these openings will be so terrific that the amount of insulation won't matter much.

How to make use of a home energy audit or free home energy use survey

A less precise and less computerized method for calculating building heat loss (or gain) is used by people who perform an "energy survey" or energy audit for a building. Home energy audit services may be free from your local utility company. The energy survey technician uses a pre-printed form whereon s/he records the areas of the building's walls, top floor ceilings, foundation walls, floors, and the number and type of windows and doors.

An "R" value is assigned to these and the sheet is used to manually calculate the building's rate of heat loss. We had one of these "free" surveys performed on a home built in 1900 when we were renovating it years ago. Regrettably the surveyor was not very observant. He rated our walls at a very high rate of heat loss by assuming that they were not insulated whatsoever (and then proceeded to try to sell us an insulation service).

What that particular home energy audit surveyor failed to notice was that the building walls had been insulated (with blown-in foam) - a condition that was quite easy to see since we had removed the building's exterior siding and wall sheathing. He just didn't look.

So while home energy audits are a great idea, make sure your auditor is awake before you believe the results of the home energy survey.

And remember that some "home energy auditors" are really trying to sell you replacement windows (very long payback time) or building insulation. (Remember the urban legend about the home energy auditor who was using a camera light meter as an "energy loss" indicator to convince home owners that they needed new windows?)

Using infra-red or thermography to screen buildings for un-wanted heat loss, leaks, or heat gain points

Home energy loss surveys using thermography or simple infra-red thermometers are a great way to pinpoint individual points of heat loss (or unwanted heat gain) in a building.

In the hands of a properly-trained expert (not a window salesman) this equipment can help find unexpected building air leaks or heat loss points even when you think that the building has already been insulated. Having a "high-R" insulated wall or ceiling is not going to be enough to make a building energy efficient if there are many unidentified air leaks or insulation voids in the building's walls, ceilings, or floors.

What is the Typical Design Temperature for Buildings and Building Insulation?

The "indoor design temperature" for a building refers to the assumed target indoor temperature that the building owner or occupants want. Typically 70 deg.F. is used unless the owner specifies something different.

The "outdoor design temperature" for a building is (for heating purposes) assumed to be the average lowest recorded temperature for each month between October and March (the heating season in most climates). If we are specifying a "design temperature" for cooling climates we'd use the average outdoor highest recorded temperature during the heating season, perhaps April through September.

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AIR CONDITIONING & HEAT PUMP SYSTEMS
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
  Find Heat Loss & Air Leaks
  Heat Loss Investigation Sequence
  Blower Door Test Data Results
  Smoke Gun for Air Leaks
  Smoke Pencil / Smoke Gun Suppliers
  Attic Energy Losses - InfraRed
  Basement Energy Losses- IR & Visual
  Duct System Air Movement
  Living Space Heat Loss
  Targets & Hidden Leak Points
  Convective Loops & Thermal Bypass Leaks
  Insulation Air & Heat Leaks
  The Bottom Line on Energy Retrofits
AIR LEAK MINIMIZATION
AIR SEALING STRATEGIES
BLOWER DOORS & AIR INFILTRATION
ENERGY SAVINGS in BUILDINGS
FIBERGLASS HAZARDS
INTERIORS of BUILDINGS
COMBUSTION GASES & PARTICLE HAZARDS
COMBUSTION PRODUCTS & IAQ
DEFINITION of Heating & Cooling Terms
HEAT LOSS in BUILDINGS
  How to measure heat movement through a wall
  How to measure building insulation
  How leaky is the building
  BASEMENT HEAT LOSS
  ENERGY AUDIT - How to Use a Free One
  ENERGY SAVINGS PRIORITIES
RADIANT HEAT
RADIANT HEAT Floor Mistakes to Avoid
RADIANT SLAB FLOORING CHOICES
RADIANT SLAB TUBING & FLUID CHOICES
  ENERGY AUDIT - How to Use a Free One
HEAT LOSS INDICATORS
HEAT LOSS PREVENTION PRIORITIES
HEAT LOSS R U & K VALUE CALCULATION
HOUSEWRAP AIR & VAPOR BARRIERS
HEAT TAPES, Heat, Insulation prevent Freeze-Up
HEATING SYSTEMS
HEATING COST FUEL & BTU Cost Table
HEATING COST SAVINGS METHODS
HEATING LOSS DIAGNOSIS-BOILERS
HEATING LOSS DIAGNOSIS-FURNACES
HOUSEWRAP AIR & VAPOR BARRIERS
INSULATION & VENTILATION INSPECTION & IMPROVEMENT
Insulation R-Values & Properties
ASBESTOS: Photo Guide to Materials / Products
Mold Growth Resistance of Foam Insulation
Table of Properties of Insulating Materials
HUMIDITY LEVEL TARGET
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSEWRAP - TYVEK INSTALLATION DETAILS
ICE DAM PREVENTION
MOISTURE, MOLD, ICE DAM LEAKS in ATTICS & ROOFS

More Information

• Asbestos pipe insulation in buildings
• Brick "Insulation" in Building Walls
• HEAT LOSS CALCULATIONS, Insulation Properties, Definitions of R, K, U values, Insulation Design
• How to Choose an Air Conditioner - BTU Chart
• How to Detect and Correct Attic Condensation & Prevent Ice Dam Leaks in Buildings
• How to Inspect Building Interiors and Building Insulation/Ventilation list of articles about building insulation inspection, defects, design, and ventilation requirements
• Insulation Materials as Indicators of Building Age
• Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
• Insulation Identification Photographs - Cellulose insulation photos, Mineral wool insulation photos, rock wool insulation photos, cotton insulation photos, balsam wool insulation photos
• Insulation Identification Photographs - Vermiculite insulation photos
• LP or Natural Gas Pressures & BTUH per Cubic Foot
• Insulation Properties, Table of R-Values, density, moisture permeability, fire safety, aging effects on various insulation materials
• Mold in Fiberglass in Insulation
• Radiant Heat Floor Mistakes to Avoid
• Rated Cooling Capacity - How to Determine Air Conditioning Equipment Rated Cooling Capacity
• Un-Vented Roof Solutions - How to Prevent Attic Condensation, Ice Dam Leaks, Roof Mold, & Roof Structural Damage in Buildings with Un-vented Roof Cavities
• Vermiculite Building Insulation & Asbestos

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