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Home Energy Rating System (HERS) Ratings, Manual J/S, ResCheck

Building departments across Long Island require heightened levels of energy efficiency for new homes. But code compliance verification of this is aspect of construction 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. You may also need to provide a Manual J and ResCheck. You will also need a HERS completion certificate at the end of construction to get your final Certificate of Occupancy. 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
Many of these municipalities also require Manual J and ResCheck.

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 considerations 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, floor, and ceiling assemblies, etc. must be designed by your architect.

What is a Manual J?
The ACCA Manual J is a heating / cooling load calculation that determines how much tonnage is required to keep a house or building at a given temperature, based upon insulation in floors / walls / ceilings, window quality / orientation, shell / duct leakage, etc. Manual S is an addendum to this report and specifies equipment selection, i.e., 2 Rheem 3-ton condensers, for example.

What is a ResCheck
ResCheck is a software program provided by the US Office of Energy Efficiency and Renewable Energy. It is used to demonstrate that insulated wall, ceiling, and floor assemblies, as well as windows and doors used in construction drawing are in compliance with NY state codes.

Note that ResCheck and Manual J are outside the scope of a HERS rating.

As of May 2020, NYS requires adherence to ECCCNYS 2020 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 WallsR20 cavity or R13 cavity + R5 continuous
(1" 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
WindowsU 0.35 / SHGC 0.40
SkylightsU 0.55
FoundationR10 continuous or R13 cavity
Slab edgeR10, 2-ft max depth
Shell Leakage3 ACH 50
Duct Leakage4 CFM per 100sf
Loads, sizing
ACCA Manual J,Manual S
Pipes in
unconditioned space
Ducts in
unconditioned space
R8, or R6 for 3" - 6", or R4.2 for less sized ducts
HERS54 (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 to operate, 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 that the first two site inspections help ensure 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, a file is created by entering all of the building parameters (sq. footage, volume, insulation, windows, etc.) into REM/Rate, a HERS rating software program. The software also generates the certificates needed 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 provided by a 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
The building shell needs to be sealed as tightly as possible. This is best done prior to drywall and insulation. This means that transitional areas traditionally left open in conventional construction, such as sill plates and rim joists, must be air-sealed. For those in construction who have not learned air-sealing, there are many resources available. Air-sealing the shell has become an essential skill for any builder. The first site inspection occurs immediately prior to insulation. We like to meet with the construction manager to ensure that the project will be on tracking. If the building is ready we can take a preliminary blower door test to see if the air-sealing target is on-track.

Insulation Inspection

Insulation needs to be in full contact with the surface it insulates
The insulation inspection is done prior to drywall. HERS raters must visually verify insulation levels for reporting. 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 neatly 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 modern energy codes, 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 we like to do a preliminary test done prior to insulation and drywall to 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 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. What was considered standard practice 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 (insulation in rafters, finished basement) and therefore not subject to duct leakage testing.