Home Energy Rating System (HERS) Ratings - for new residential constructionBuilding departments across Long Island require heightened levels of energy efficiency for new homes. But like some other trades, verification of this is outsourced from the building department to 3rd party, certified HERS raters. If you're building a house or residential building in Long Island or New York City, you will probably need a HERS Compliance Certificate before you can break ground. We provide clear and detailed written reports, unique to the local HERS trade, with specific instructions following the plans review and each inspection, in order to ensure that your construction staff stays on track throughout the project. Towns in Long Island that have incorporated HERS ratings into their codes include:
- Town of Brookhaven
- Town of Babylon
- Town of Hempstead
- Town of Huntington
- Town of Islip
- Town of North Hempstead
- Town of Oyster Bay
- Town of Riverhead
- Town of Southampton
A HERS rating is a scoring system used to determine the performance of a house with respect to energy efficiency and conservation. It takes into account such parameters as insulation levels, window U-factors, efficiency of heating and cooling equipment, building shell leakage and duct leakage, among other things. The resulting score is called the HERS index.
A HERS rating is not a design service. While we can offer suggestions for energy upgrades, all wall / ceiling assemblies, etc. must be designed by your architect.
As of October 2016, NYS requires adherence to IECC 2015 energy codes. Here is a quick breakdown of what is required by state code. Note that your town's requirements may be more stringent (but not less stringent). New York City and Long Island fall into Climate Zone 4.
|Frame Walls||R20 cavity or R13 cavity + R5 continuous |
(XPS) foam boards on outside of shell
(brick, block, ICF)
|R8 or R13 if more than half|
the insulation is on the interior
|Windows||U 0.35 / SHGC 0.40|
|Foundation||R10 cont. or R13 cavity|
|Slab edge||R10, 2-ft max depth|
|Shell Leakage||3 ACH 50|
|Duct Leakage||4 CFM per 100sf|
|ACCA Manual J,Manual S|
|R8, or R6 for 3" or less sized ducts|
|HERS||54 (performance alternative)|
Lower HERS ratings are better. A HERS index of...
- 100 is equivalent to a house built to energy codes of 2006
- 130 performs 30% more poorly than a HERS 100 house
- 54 performs 46% better than the HERS 100 house. It is an optional performance-based alternative to full compliance with IECC 2015.
- 0 is a net-zero energy house and would have on-site power generation to generate all the power it needs, such as solar or wind
The typical HERS rating includes:
- A plans review
- Air-sealing site inspection (done prior to insulation)
- Insulation site inspection (done prior to drywall)
- Final site inspection (done after building completion). From experience, we can atest that the first two site inspections help ensure a successful outcome to final testing.
How a HERS rating worksWe can work with home builders to help meet the energy codes and we try to make the process and smooth as possible. The HERS process generally runs like this:
Plans review and recommendations
The initial (proposed) HERS index is determined by a plans review, which is done before ground-breaking to make sure that the house, as designed, can attain the target HERS index. Sometimes modifications to the plans are needed to assure the house will pass, but they are usually minor changes. Once the plans review has been completed, site inspections are done during different phases of construction to make sure that the project is on track and will be built according to the agreed energy-conservation measures. During a plans review, we enter all of the building parameters into REM/Rate, a software program used specifically for HERS ratings. The software also generates the certificates you need for the building department. We can also suggest energy upgrades at this point. We refer to the plans review file throughout the rating process until completion. Before ground can be broken, most municipalities will require a Compliance Certificate to be submitted by the HERS rater. This form is generated as a culmination of a plans review so that the municipality can see that the project will reach the target HERS index.
Fiberglass-insulated houses are more challenging to air-seal than houses done with spray foam. If your construction staff has not built a house according to the IECC 2015, extra attention will be needed to ensure project success. Many new houses are insulated with spray foam, which makes the air-sealing process much simpler.
Other alternatives to fiberglass are encouraged:
- Dense-pack blown-in cellulose is quite useful for filling voids.
- Spray polyurethane foam (SPF), although more expensive, provides air sealing as well as well as a higher R-value per inch (in the case of closed-cell foam).
- Adding extra foam board insulation with taped joints under exterior siding can boost the performance of the house as well minimize or eliminate the thermal bridging that occurs with a typical stud wall.
The final site inspection involves several tests and takes a few hours
Blower door testing for building shell air-tightness
A blower door is used during the final inspection to measure shell leakage, although some builders of high-performance houses opt to have a preliminary test done prior to insulation and drywall to identify leak points and to make sure the project is on track. Code requirements in NYS (IECC 2015) mandate that shell leakage must not exceed 3 air changes per house at 50 pascals of pressure (3 ACH50), which is roughly equivalent to 0.21 natural air changes per hour. 3 ACH 50 means that if the blower door runs for an hour, 3 times the volume of air that would fit into the entire house would pass through the fan.
Duct blaster testing for duct air-tightness
Proper HVAC duct sealing has historically been an afterthought at best by many HVAC installers, but this practice (or lack of practice) can result in significant sustained energy losses as well as pressure imbalances in the building. Duct sealing and testing is required by NYS building code (IECC 2015), but has not been historically enforced very often. This is changing and what was considered "acceptable" in the past no longer passes muster. Sealing for ducts in unconditioned spaces must be done with mastic or UL-181 mastic tape and testing must result in state-code-required leakage-to-outside of no more than 4 CFM (cubic feet per minute) per 100 square feet of conditioned floor area. HVAC subs should be made aware of these requirements to avoid project delays and extra costs. HVAC installers will find the some towns in long island are now requiring certtificates for duct leakage testing on retrofit work for existing houses. For new construction, many headaches can be avoided by designing the house so that all ducts are within conditioned space and therefore not subject to duct leakage testing.
Combustion Appliance Zone testing for all fuel-burning appliances
Combustion safety testing is required for all fuel burning appliances, including furnaces, boilers, water heaters and ovens. If carbon monoxide levels are too high or draft is too low, repairs must be made. Note that sealed-combustion heating appliances perform much better with respect to draft and depressurization than atmospheric, or natural draft, heating equipment.