Energy modeling services:
- Home Energy Rating System (HERS) Ratings
- EnergyStar Ratings for Single and Multifamily Buildings
- Manuals J and S
- ResCheck
- Blower Door Testing
- Duct Leakage Testing
Building departments across Long Island and New York City require heightened levels of energy efficiency for new homes as compared to 15 - 20 years ago. But code compliance verification of this aspect of construction is outsourced from the building departments to 3rd-party certified HERS raters, as specialized training and testing equipment is required.
If you're building a house or residential building in Long Island or New York City, you may well need a
HERS Compliance Certificate before you can break ground and a
HERS final certficate at the end of the project. You may also need to provide
Manuals J & S and
ResCheck.
Some municipalities on the North Fork do not require HERS ratings, but do require Manuals J & S, ResCheck, blower door testing, and duct leakage testing. Duct leakage testing is often required by municipalities where new ductwork is installed in existing houses. Always verify what you'll need directly with the authority having jurisdiction.
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.
Lower HERS indices are better. A HERS index of...
- HERS 100 is equivalent to a house built to energy codes of 2006
- HERS 130 performs 30% more poorly than a HERS 100 house
- HERS 54 performs 46% better than the HERS 100 house.
- HERS 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
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. More about HERS rating below.
What is a EnergyStar?
EnergyStar is a voluntary construction standard developed by the US EPA. While it was initially synonymous with a HERS rating, it now describes single- and multi-family housing built and independently verified to be at least 10% to 20% more energy-efficient than standard code-level, i.e., HERS-rated, construction. These buildings feature superior insulation, high-performance windows, tightly sealed construction, and efficient HVAC systems, leading to lower utility bills, increased comfort, and reduced greenhouse gas emissions.
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 at a given indoor 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, and how the equipment would meet the heating / cooling needs of the building.
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 drawings are in compliance with presrciptive NY state codes.
Note that ResCheck and Manual J are outside the scope of a HERS rating.
Energy Codes
As of May 2020, NYS requires adherence to ECCCNYS 2020 energy codes, although some municipalites will allow performance trade-offs. Here is a quick breakdown of what is required by state code. Note that your town's requirements may be more stringent. New York City and Long Island fall into
Climate Zone 4. The table below shows prescriptive code requirements.
| Ceilings | R49 |
| Frame Walls | R20 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 |
| Floors | R19 |
| Windows | U 0.35 / SHGC 0.40 |
| Skylights | U 0.55 |
| Foundation | R10 continuous or R13 cavity |
| Slab edge | R10, 2-ft max depth |
| Shell Leakage | 3 ACH 50 |
| Duct Leakage | 4 CFM per 100sf of area served |
| Cooling Loads, sizing | ACCA Manual J,Manual S |
Pipe insulation in
unconditioned space | R3 |
Duct insulation in
unconditioned space | R8, or R6 for 3" - 6", or R4.2 for less sized ducts |
| HERS | 54 (performance alternative) |
How a HERS rating works
The typical HERS rating includes:
- A plans review, before construction begins
- 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.
We can work with home builders to help meet the energy codes and we try to make the process and smooth as possible. 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. The HERS process generally unfolds thusly:
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. Modifications to the plans may be 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 constructed 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 initial 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 their target HERS index.
Air-Sealing inspection
Tub wall needs complete air barrier prior to tub installation
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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, although this is task often subcontracted out to the insulation contractor. 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 track. If the building is ready at this stage (depending upon its design), 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
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The insulation inspection is done prior to drywall. HERS raters must verify and document insulation levels for reporting purposes. 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's stated R-Value.
Fiberglass-insulated houses are more challenging to air-seal than houses done with spray foam. Generally, it is not possible to perform a preliminary blower door test on fiberglass-insulated houses. 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 spaces around pipes.
- Spray polyurethane foam (SPF), although more expensive, provides air sealing as well as a higher R-value per inch (in the case of closed-cell foam).
- Installing 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.
Blower door testing for building shell air-tightness
A blower door is used during the final inspection to measure shell leakage (although if possible 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 leakage 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 subcontractors agree to these requirements in their scope of work 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 instead of top ceiling, finished basement) and therefore not subject to duct leakage testing.
