Energy efficiency is the only proven cost effective bridge to the changes that will be impacting energy sources and energy policy in the coming years. The low hanging fruit comes from improving the energy efficiency of the approximately 100 million existing homes and commercial buildings.
There are a wide variety of approaches that can be used when performing an “energy audit.” This article will describe a Comprehensive Home Energy Audit (CHEA). In a CHEA, diagnostic data is entered into special U.S. Department of Energy approved software, resulting in a rating score on the Home Energy Rating System or HERS Index. (homeenergyteaminstitute.com)
A successful comprehensive audit will:
• Identify the current conditions (survey, discussion, performance tests, energy modeling) to establish a base line
• Analyze and weigh the options for energy, comfort, and IAQ improvements (best practices, safety considerations, energy analysis; what is the baseline performance to improve?
• Organize the order of improvement based on owner desires, cost and safety
• Facilitate energy upgrades by the contractor (audits without improvement are of no value)
• Verify that the outcome meets or exceeds the objectives (base vs. improved, owner satisfaction and performance results).
HVAC contractors who wish to deliver comprehensive audits must add an understanding of building science to their portfolio and must have an understanding of what is known as “the house as a system.”
A Comprehensive Energy Audit gives a holistic evaluation of the home. HVAC contractors who wish to deliver comprehensive audits must add an understanding of building science to their portfolio and must have an understanding of what is known as “the house as a system.” Adding the skill set of Energy Rating/Auditing or Home Performance is essential to effective action. Capture this knowledge from the Home Energy Rating industry (HERS Rater or HERS Energy Auditor from RESNET) or the Home Performance Improvement industry (Building Analyst from BPI). The best known programs are the Texas Home Energy Rating Organization’s Residential Audit, or the EPA Home Performance with Energy Star Program.
Basic Evaluation Elements of CHEA
A CHEA begins with a proposal that lists the proposed scope of intended activities, an explanation of the process, and anticipated outcomes. When accepted, the auditor begins the process with a homeowner survey. Examples of surveys and survey questions abound on the Internet ,and essentially cover the basics of what it’s like to live in the space.
• It’s valuable to capture 12 months (or more) of utility bills.
• It’s important to understand if there are comfort issues such as hot and cold spots, drafts, humidity problems, etc. in the home.
• The owner will have comments about the mechanical systems, appliances, lighting and other power using elements.
• Inquire about respiratory issues and identify potential solutions to indoor air quality (IAQ) issues.
• Completely cover every element on the checklist and refer to it repeatedly to determine the eventual order of improvement recommendations.
The Audit begins with visual inspections of basic elements:
1. Exterior evaluation (roofs, foundations, attached garages, walls, doors and windows).
2. Inspection of attics, basements and/or crawl spaces.
3. Interior evaluation (floors and ceilings, HVAC, domestic water, appliances, lighting).
4. Performance tests (natural gas leak analysis, home tightness, duct tightness, airflow, carbon monoxide (CO) testing.
5. Energy analysis, load calculations, and recommendation strategies. 6. Scope of work/proposals and evaluation.
7. Performance of energy improvement actions.
8. Test out — verify improvement.
How to Evaluate Home Exterior
1. Draw a sketch of the exterior of the home with measurements and roof configuration, and place and measure the windows. Look for potential water and air intrusion areas.
2. Look for flaws in the condition of the siding, trim, and fascia. Look for cracks in the brick exterior and shifts in headers, door jambs, or window sills.
3. Observe any foundation issues. What methods are used to move roof water away from the foundation?
Evaluate Attics, Crawl Spaces, Basements
Attics — Check to see that all chaises are capped and sealed. Areas around ductwork, chimneys, flue stacks, and plumbing stacks are areas where you’ll find gaps, holes, and other types of thermal bypasses. Check the level and the distribution of the attic insulation. Mechanical systems are at the core of the energy use in the home. Check these systems carefully.
Basements/crawl spaces —What and where is the insulation? Where is the thermal boundary for the home? Is the area inside or outside of the thermal envelope? What is the level of air sealing between the basement/crawl space and the exterior; and the basement and the first floor? Look at the walls and floors for cracks, signs of air infiltration, and the telltale problems caused by excessive moisture or bulk water. Does the basement have or need sump pumps?
Inspect Home Interior
Interior, floors, walls, and ceilings: The big enemy of energy and IAQ in an existing home is water—both vapor and in bulk. Check for moisture problems on window sills, in the living space under windows, behind furniture, in closet corners, and around tubs, showers and restrooms.
Windows — You’ll want to know the size and type of window enclosure, single or double (or more) panes and whether or not there is any low emissivity coating on the windows. Doors should have functional weather stripping. You should not be able to see light around any of the door edges.
Walls — You can remove the cover of an electrical plate and probe the cavity for insulation. Infrared thermography is also good for verifying the presence of insulation and determining strategies for areas where the insulation is missing or where gaps and thermal bypasses exist. Ceilings — Are the supply registers sealed to gypsum board? Are their cracks or other signs of shifting foundation? Are there any signs of water damage?
Age and condition of the appliances — There may be value in a total or partial appliance upgrade. Despite intense marketing, there remains a huge opportunity to shift owners to compact fluorescent lighting. A survey of lighting and lighting fixtures should be used to calculate potential energy savings.
Plug load — There’s a major increase in the quantity of electrical devices that use electricity. Capturing energy usage for the sum of these plug load devices is important to understanding the impact of electricity usage and making suggestions for lowering over all energy use.
HVAC and domestic water — HVAC systems are central to energy efficiency. They’re the largest energy using appliances. Proper installation is a key to safe operation. It’s equally critical to properly commission the equipment, and perform regular and systematic maintenance, to re-commission the equipment and keep everything operating properly.
Performance Tests
The most common audit performance tests are home and duct tightness tests. These are tests that determine if there are significant energy losses in the thermal envelope, or leaks in the duct system. When combustion appliances are within the thermal boundary, it’s important to test for carbon monoxide. Sealing the homes’ thermal bypasses can impact the pressure boundaries of the home and have a dynamic (and sometimes very negative) impact on what happens to the products of combustion. The key is to address safety first and don’t fail to understand the implications of how the changes impact combustion gasses. Flow hoods for measurement of CFM at the grille can provide a base line for improved air flow — after sealing or replacing the duct. Smoke pencil and infrared cameras make it easier to see where there are potential bypasses.
Energy and Analysis
A completed field audit can be input into detailed energy models and load calculation forms. Reports can show the baseline building and the improvement from varies measures or a basket of energy measures. Loads are essential in determining the size and capacity of replacement HVAC equipment. Based on the goals and objectives found in the survey, the report should describe what exists, what’s possible, a ranking of priority actions, and offer detailed scopes of work, or a comprehensive proposal for energy improvement work.
Value to Your Business
The purposes of developing corporate capacity and knowledge to effectively deliver comprehensive audits are three fold:
1. Increase the quality of your service offerings.
2. Grow the professionalism of your organization.
3. Be rewarded for delivering superior value to your clients.
Developing and incorporating a comprehensive energy audit methodology within your company should not be a quick “bolt on” service designed to address the opportunities from a specific government or utility program. An audit that delivers real value to the homeowner is the outcome of a thoughtful approach that incorporates your company’s historical experience, while adding the tools and knowledge of building science. Best results come if your company’s mission is to deliver information that leads to verifiable energy improvements for the home. An audit process designed for sales success and not client value is likely to be a long term failure. Look out for your customer’s best interest. It’s the business strategy most likely to lead to energy improvements and long- term business success.
Steve Saunders is CEO of Tempo Mechanical, Irving, TX and Contracting Business.com’s 2003 Residential Contractor of the Year. He can be reached at 972/579-2003.
This article is based on “How to Conduct a Residential Energy Audit,” which Steve Saunders presented at HVAC Comfortech 2009, in Nashville, TN. HVAC Comfortech 2010 will be Sept. 22-24, in Baltimore, MD. Visit hvacrweek.com for additional information.