Why Energy Star?
There are quality standards for almost all products you buy, and you will always find a stamp that shows that someone checked to see that the product met a quality
standard - that is, until you come to the most expensive product in everyone's life: their home.
A home has expectations of standing for decades in spite of Mother Nature’s best effort to destroy it, but the warranty is only for one or two years and any short cuts in building quality will surely show up long before the life expectancy of the home.
There are building codes that local authorities use to maintain some sort of consistency, but most are focused on conformance and not quality. Building contractors rely heavily on their subcontractors to meet specifications and quality levels and very little if any testing is done to confirm operational conformance and quality.
The biggest challenge associated with home building is the homes ability to keep the outside air out and the inside air in; how well the home is insulated and how tight the home is to air and moisture leakage. The difference between a tight high quality built home and a leaky low quality built home can be a 60% difference in energy bills, and a draughty uncomfortable and unhealthy internal living space.
Wouldn’t you like to know where your home is and what you can do to improve your standard of in-home living? The only way to find out is to test it or build it to a recognized, verified and tested standard.
The Department of Energy (DOE) and the Environmental Protection Agency (EPA) have combined forces in developing a set of standards that help homeowners establish how to calibrate the energy efficiency of their homes; the result is the Energy Star program. It’s mostly known for its energy ratings on household appliances, but it also has a rating system for energy efficiency in new and existing homes.
Energy Star is based on the International Energy Conservation Code (IECC); these standards are used by the Residential Energy Services Network (RESNET) and their Home Energy Rating System (HERS). The IECC is also used by many local government building departments as their inspection and conformance standards.
During an energy analysis the specifications in the IECC standard are used as a reference home, which represents 100 on the HERS scale (below), all homes tested are compared to that reference. A home using more energy than the reference home returns a higher number on the scale and those homes using less energy return a lower number; the lower the number the better. To meet an Energy Star rating your home has to obtain a HERS rating of 85 or less, which represents 15% less energy use than the reference home. As can also be seen the average existing home returns an average rating of 130, or use 30% more energy than the reference home.
Why is Energy Star so important to the home buyer? It provides a verified certificate of quality and a standard for knowing how efficient or not the home you are buying or building is. Even though new homes are inspected by town inspectors during the construction process or a home inspector for an existing home they do not inspect to the level of an energy rater or energy consultant and the homes are not tested and there isn’t a measured result.
The Energy Star HERS rating process has three steps for a new home and one for an existing home. The first phase for a new home is a software simulation based on architectural drawings and construction materials; it includes importing climate data, building orientation and all the building dimensions into a software model. Also imported are window and door specifications and orientation, insulation levels and mechanical specifications for heating, ventilation and air conditioning systems, hot water generation, solar energy and electrical apparatus.
It’s quite a complex model that predicts the heating and cooling load for the home; the heating and cooling load represents how much heat you loose through the envelope of your home during the winter and how much heat comes into your home through the envelope during the summer. These numbers tell you how big you’re heating and cooling system needs to be to replace those losses. It also tells you the expected cost for energy you will need to support the home and the projected HERS rating.
It’s a very powerful tool for analyzing what if scenarios; unfortunately, it is only as good as the quality of the inputted data which is critical for success and should be checked thoroughly. My experience has shown multiple input errors can occur multiple times.
The second stage is a physical inspection of the homes leakage and insulation conformity to simulation; it evaluates envelope tightness, insulation levels, sealing of electrical and plumbing installations and ducting if specified before drywall is installed. This is the best time to make improvements if needed.
The final stage is the inspection and testing stage; using a blower door tester the home is depressurized and the amount of air leaking into the home is measured; the amount of air measured determines if the home is tight or leaky and if it meets the simulation expectations. If a forced air heating and cooling system is fitted the duct system will also need testing for leakage as in many cases the duct system leaks both inside and outside the buildings envelope and causes no end of problems with leakage and pressurization.
Heating, ventilation and cooling (HVAC) system selection and installation is most critical. Sizing the system must be done through simulation software and the installation has to follow very specific procedures; failure to do this can cost a homeowner a lot of wasted energy and money. The final results of the inspection and testing are programmed into the RESNET software program and the results and HERS rating presented. These are the results certified.
For an existing home only stage three is performed and as stage two cannot be performed a best effort analysis of the insulation levels and construction techniques are programmed into the software and a HERS rating obtained. These results are used to determine the cost savings and effectiveness of any energy retrofit.
For new homes the basic materials used may meet the requirements for an energy efficient home but so much of the resulting performance is based on construction quality. Even though builders are becoming sensitive to the energy needs of tight building, few understand the energy implications and even fewer take the time to seal and build a tight home. This is very apparent with track homes where time and cost take precedent.
As with all professions there are good and not so good ratings companies, being able to detect which requires knowledge and monitoring. The software tools used are as good as the data imported and that is as good as the person who collected the data and programmed the software. Many raters work for contracting firms and have high integrity, but there is a temptation to generate needless solutions and cost to non existent problems. An independent and knowledgeable advocate can help in this regard.