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Home Energy Rating System (HERS) Ratings - for new residential construction in Long Island

Building departments across Long Island require new 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. Aberdeen Building Consulting provides clear and detailed written reports, unique to the local HERS trade, with specific instructions following the plans review and each inspection, which will be critically useful to make sure 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
What is a HERS rating?
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.

CeilingsR49
Frame WallsR20 cavity or R13 cavity + R5 continuous
(XPS) foam boards on outside of shell
Mass walls
(brick, block, ICF)
R8 or R13 if more than half
the insulation is on the interior
FloorsR19
WindowsU 0.35 / SHGC 0.40
SkylightsU 0.55
FoundationR10 cont. or R13 cavity
Slab edgeR10, 2-ft max depth
Shell Leakage3 ACH 50
Duct Leakage4 CFM per 100sf
Cooling
Loads, sizing
ACCA Manual J,Manual S
Pipes in
unconditioned space
R3
Ducts in
unconditioned space
R8, or R6 for 3" or less sized ducts
HERS54


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 and is the target required by most towns
  • 0 is a net-zero energy house and would have on-site power generation, such as solar or wind
What does the service include?
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 the the first two site inspection greatly improve the odds of a successful outcome to final testing.

How a HERS rating works

We 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 and determine whether they would be cost-justified. 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.

Air Sealing inspection

Tub wall needs complete air barrier prior to tub installation
Prior to drywall and insulation, the building shell needs to be sealed as tightly as possible. This means that transitional areas traditionally left open in conventional construction, such as sill plates and rim joists, must be air-sealed. We provide instructions as to how to go about doing this sealing, which for anyone familiar with construction, will not be a stretch. Some extra labor and minimal materials are all that is required. For example, the photo on the left shows the tub wall prior to tub installation. We see that there is a solid air barrier between the wall and tub.

Insulation

Insulation needs to be in full contact with the surface it insulates
The insulation inspection is done prior to drywall. Fiberglass batt insulation, the most common form of insulation, has been installed in practically every house built since 1950. It is also one of the most misunderstood and mis-installed products. To attain its labeled R-Value, it must be installed touching all six sides of the cavity (front, back, sides, top and bottom), with no compression. This means no stapling to sides of studs. Also, insulation must be cut to fit around pipes and wires. Moreover, it should not be subject to wind-washing, which would occur, for example, at soffit vents. Fiberglass is often not installed correctly, which results in its R-Value compromised to as little as 50% or less of the label.

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, some extra attention may be needed for them to ensure project sucess. 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

Blower door tests shell leakage
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 make sure the project is on track. Code requirements in NYS mandate that shell leakage must not exceed 3 air changes per house at 50 pascals (3 ACH50) pressure, 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

Duct blaster measures duct tightness
Proper air duct sealing has historically been an afterthought 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 often enforced. Duct sealing should 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 brought on board with the project to avoid project delays and extra costs. HVAC installers may find the some towns in long island are now requiring certtificates for duct leakage testing on retrofit work for existing houses.

Combustion Appliance Zone testing for all fuel-burning appliances

High-efficiency furnace
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 heating equipment.

Worst case depressurization testing for potential backdrafting

A manometer is used to check pressure differences in the building
Exhaust fans, HVAC fans, and clothes dryers can depressurize a tight house to the point where backdrafting could occur on natural-draft fuel-fired heating equipment, resulting in dangerous combustion gases entering the house. We make sure that these conditions do not occur by creating a worst-case pressure scenario in the building. If pressure levels are inappropriate, repairs must be made before the house can be occupied.

Gas leak testing for gas pipes

Gas pipes are checked using a combustible gas detector
We verify gas-tightness of gas pipes. Leaks are sometimes discovered on new work.


Exhaust duct design


Exhaust ducts for bathrooms, kitchens and laundry are oftentimes left as an afterthought. But they must be constructed correctly to function properly. As part of the service, instructions for correct ducts specs are provided and verified during the site inspections.