One day, not too far in the future, every new home will be constructed to a zero-energy standard. This is just my opinion, but a look at the current codes, especially the energy codes, and we see things moving in that direction. Last week we started a discussion on how to achieve a Zero Energy Home (ZEH), the first step is to meet the requirements of Energy Star. This week is all about the requirements of ZEH.
The definition of a Zero Energy Home is one that consumes roughly the same amount of energy as is produced on site by some renewable source. Some homes currently being built are zero energy ready, meaning they meet the guidelines for a ZEH, but do not have the energy production capability installed at the time of construction. Energy production is planned to be installed at a later time.
There are two methods to achieve a zero-energy certification, the first is through the prescriptive path, meaning the requirements of the program are met through a “checklist”. The second option is the performance path, or a home that is designed to meet the requirements, usually by a professional designer, Home Energy Rating System (HERS rater), or architect using modeling software. There isn’t a lot of discussion about the performance path, the design will be completed by a professional and the builder will follow the design. We will look at the prescriptive path requirements, which will still need to be certified by a third party, typically a HERS rater.
More ZEH information can be found at: https://www.energy.gov/eere/buildings/zero-energy-ready-home
There are seven mandatory requirements to achieve ZEH certification.
- Energy Star
- The home must be certified Energy Star version 3 or 3.1. See last week’s blog. Construction Design-Zero Energy, Step One
- All windows must meet the Energy Star Requirements for your climate zone.
- Ceiling, wall, floor and slab insulation must meet the 2012 or 2015 IECC levels. Minnesota’s current code is the 2012, an interesting note is because the 2012 code has been in force for more than 12 months, ZEH requires the use of the 2015 IECC.
- Duct System
- The duct system must be installed within the air and thermal boundary of the home.
- There are exceptions to this requirement. See the ZEH website for more information. I recommend keeping the ducts within the building envelope for our climate, (Climate Zone 7). Ducts that leave the envelope, such as in an unconditioned attic or crawl space, need very specific air sealing, insulation and testing to be completed on the system, adding substantial costs.
- Water Efficiency
- Hot water delivery systems must meet the EPA’s WaterSense program. https://www.epa.gov/watersense
- No more than .5 gallons in the pipes between the water heater and plumbing fixture.
- There are requirements when using hot water recirculation systems, such as occupant control. The system is not allowed to constantly recirculate.
- Less than .6 gallons of water is allowed to flow through the water lines before hot water is delivered to the fixture.
- See the ZEH web site for a detailed description of water efficiency requirement.
- Lighting and appliance
- All refrigerators, dishwashers and clothes washers must be Energy Star certified.
- 80% of all lighting fixtures and bulbs must be Energy Star certified. (The requirement of Energy Star 3.1 in 90%)
- All bathroom ventilation fans and ceiling fans must be Energy Star certified.
- Indoor air quality
- The home must be certified under the EPA’s Indoor airPLUS program, which is an “add-on” to the Energy Star program.
- Indoor airPLUS include improved moisture control, HVAC, combustion venting, and radon systems along with the inclusion of low emitting building materials while the home is being constructed.
- More information can be found at: https://www.epa.gov/indoorairplus
- Renewable Ready
- The home must have a completed photovoltaic solar panels (PV)-ready checklist, if PV is not installed during construction.
- The requirements of the checklist include; the location of the home must be able to support at least 5 kWh/m²/day average, not have significant shading and have the proper roof area and orientation to support PV panel production.
Why would anyone want to spend the extra time and money to build a home certified as either Energy Star or Zero Energy? The first reason is to reduce or eliminate energy costs. Imagine moving (or retiring) to a home that you know will have no or very low costs of operation. Most of these homes will have better indoor air quality and higher levels of comfort, and be durable, lasting for generations. There may be tax incentives and energy efficient rebates available to help off-set the increased cost of construction. In my area, rebates through utility companies are available when purchasing energy star appliances and high efficiency heating and cooling equipment, some rebates for certain equipment, such as a ground source heat pump, may amount to well over $1,000. A good website to find available incentives in your area is: http://www.dsireusa.org/. By the way, Minnesota is second only to California for the number of available policies and incentives to help with energy efficiency measures.
Another reason is hopefully value is added to the home. I say “hopefully” because the real estate community is just beginning to account for energy efficient measures installed in homes. This will improve over time as more buyers begin looking for efficient homes.
Lastly, bragging rights. As an energy auditor, I’ve has several conversations with homeowners who indicated they requested an energy audit based on comparing what their neighbors are paying for heat or electricity. Paying no or very little for utilities will be the envy of the neighborhood.
If you are planning a new home, or looking at a major renovation in an existing home, I recommend at least looking into both the Energy Star and Zero Energy programs. Even if the home is not certified, many of the requirements can easily be incorporated into the design. Many energy efficiency choices will be for the life of the home.