Blower Door Testing Concord MA - Quick Facts
Local energy code in Concord
- Concord adopted the Massachusetts Specialized (Opt-In) Energy Code effective January 1, 2024; the Stretch Code applies as the baseline. IECC Climate Zone 5A.
- Beyond the Stretch baseline, new mixed-fuel homes must be pre-wired for future electrification and add on-site solar where there is significant unshaded roof space.
- All-electric new homes must use heat pumps for space heating and hot water; fossil-fuel homes over 4,000 sq ft must reach net-zero (HERS 0), and new multifamily over 12,000 sq ft must meet Passive House.
- Concord also participates in the Massachusetts Municipal Fossil Fuel-Free Building Demonstration Program - new construction and major renovations must be built fossil-fuel-free (all-electric), a step beyond the Specialized Code.
Blower door requirement in Concord
- New homes in Concord must test at 3.0 ACH50 or tighter under the Massachusetts Stretch Code (Specialized Code town).
- Air-leakage testing is mandatory, measured with a calibrated blower-door fan to the RESNET / ASTM protocol - there is no inspection-only substitute for the result.
- Companion duct leakage limit: 4 CFM25 per 100 sq ft of conditioned floor area when ducts run outside conditioned space.
- Same-day preliminary results; final report in 24-48 hours, filed with the Concord building department.
2026 Mass Save incentives in Concord
- A tight result unlocks Mass Save all-electric incentives ($7,500 to $25,000 per new single-family home); an all-electric renovation testing at 3.0 ACH50 or better reaches the Level 2 tier, up to $30,000.
- Incentives require a Mass Save-approved, RESNET-certified HERS rater.
RESNET-certified · 15,000+ ratings completed · 5.0 stars across 135 Google reviews · (617) 501-6788
Blower Door Testing Concord MA
Certified blower door testing in Concord - we measure your home's air-tightness in ACH50, pinpoint leaks, and document a passing result for your building permit.
Air-tightness at a glance
Blower Door Testing Concord MA
A blower door test is the code-required way to prove how airtight a home in Concord really is. A calibrated fan depressurizes the house to 50 Pascals so we can measure exactly how much air leaks through the envelope, reported as air changes per hour (ACH50). New construction must reach 3.0 ACH50 or lower, while remodels are allowed up to 5.0 ACH50.
| Project type | Max ACH50 | Notes |
|---|---|---|
| New construction | 3.0 or lower | Mandatory blower-door test under R402.4.1.2 |
| Remodel / alteration | 5.0 | Realistic target for existing assemblies |
| Addition < 1,000 sq ft | Exempt* | May be exempt from testing (R502.3.1) |
| Passive House / Specialized | 0.6 | Whole-building test, Phius/PHI protocol |
*Confirm with your local building department. Requirements per the 2025 MA Stretch Energy Code Technical Guidance.
How Blower Door Testing Works in Concord
The fan mounts in an exterior doorway and holds the home at a fixed 50-Pascal pressure difference - about what a 20 mph wind would exert. The airflow required to maintain that pressure, in CFM, converts to ACH50 using the home's conditioned volume.
The code converts the result to Q50 (CFM at 50 Pa) with Q50 = (Volume × ACH50) ÷ 60. A 2,700 sq ft home at 2 ACH50 works out to roughly 810 CFM50.
Keeping Heat In During Concord Cold Spells
During a New England cold snap the stack effect goes to work: warm indoor air rises and slips out near the top of the house, and that pulls cold outdoor air in through gaps down low. The colder it gets, the harder this effect pushes - so a leaky home loses the most heat exactly when it can least afford to.
A tight, tested envelope shrinks the infiltration share of your heating load. That lets the equipment keep up during cold spells, holds rooms at a steadier temperature between cycles, and often lets a designer right-size the heating system rather than oversizing it to cover leakage.
Lower heating load
Less infiltration means a smaller winter heat-loss load and equipment that can keep up.
Retain paid-for heat
Warm air stays in the living space instead of escaping out the top of the house.
Steadier comfort
Fewer cold-floor drafts and a temperature that holds between heating cycles.
Where Concord Homes Leak Air
During depressurization the leaks are exaggerated, making them easy to find. In Middlesex County's older housing stock the usual suspects are rim joists, top plates, attic hatches, recessed lights, and penetrations for plumbing and wiring. Coastal and exposed sites feel wind-driven infiltration most, so a tight, verified envelope pays back quickly here.
Best Fit for Projects Like
- Homes chasing Passive House or net-zero targets
- New single-family homes needing a code compliance test
- Gut renovations and deep-energy retrofits
- Custom and high-performance builds
- Additions over 1,000 sq ft that trigger testing
Blower Door Testing Concord MA Facts
When the test happens
The blower door test is typically run near completion, once the air barrier, windows, and penetrations are sealed but while any needed corrections are still easy to make.
Cold snaps magnify leakage
Infiltration heat loss scales with the indoor-outdoor temperature difference, so a leaky envelope bleeds the most heat exactly when you need it most - during a deep freeze.
Older housing stock
Much of New England's housing predates modern air-sealing, so existing homes here often start well above 10 ACH50 - leaving large, cost-effective savings on the table.
Small-addition exemption
Additions under 1,000 sq ft can be exempt from air-leakage testing under R502.3.1, though the connected existing home may still benefit from a test.
Trusted for Blower Door Testing Concord MA
As a builder, I need accurate and dependable HERS ratings to keep projects on track. This company never disappoints. Always on time, always professional.
I had an excellent experience. Friendly, knowledgeable, and very responsive. I will definitely be coming back.
I worked with this HERS rating company in South Boston on a remodel project and was able to get back 30,000 in rebates.
Our Massachusetts Service Locations
Serving clients from our Massachusetts locations in Everett, Somerville, and Framingham.
Everett Location
371 Main St
Everett, MA 02149
Somerville Location
519 Broadway
Somerville, MA 02145
Framingham Location
68 South St
Framingham, MA 01702
FAQ About Blower Door Testing Concord MA
How tight is a Passive House?
Passive House projects on the Specialized Code path target around 0.6 ACH50 - roughly ten times tighter than base code - verified with a whole-building blower-door test.
What ACH50 does new construction need to pass?
New residential construction in Massachusetts must measure 3.0 ACH50 or lower. Many high-performance homes come in well below that figure.
Do you work with builders and homeowners?
We work with builders, remodelers, designers, and homeowners - from single tests for permit sign-off to pre-drywall diagnostics that catch problems early.
What documentation do I receive?
You receive the measured ACH50 result on a RESNET/HERS-style report suitable for the building department, plus notes on any sealing performed.
How is ACH50 converted to CFM?
The code uses Q50 = (conditioned volume x ACH50) / 60. For example, a 2,700 sq ft home with 9 ft ceilings at 2 ACH50 equals about 810 CFM50.
When in construction should the test be done?
A pre-drywall diagnostic test is ideal for catching leaks while they are easy to reach, followed by a final compliance test near completion.
Get Started With Blower Door Testing Concord MA
Book a certified blower door test and get a permit-ready air-tightness report. Call 617-501-6788.
HERS Ratings Across Concord and Nearby Communities
Home Energy Efficiency Consultants rates new homes, additions, and major renovations throughout Concord — including Concord Center, West Concord, and Nine Acre Corner. Every Concord project is filed with the Town of Concord Building Division, and we handle the energy model, blower door and duct leakage testing, and the compliance paperwork from start to finish.
We also serve the communities right around Concord, including Acton, Lincoln, Bedford, Carlisle, and Sudbury. Our Framingham office at 68 South St is the closest of our four Massachusetts locations — see our Framingham office or call (617) 501-6788 to get a Concord rating on the schedule.
Concord Specialized Energy Code — HERS Index Targets
Concord enforces the Massachusetts Specialized (Opt-In) Energy Code. The required HERS score depends on fuel type and project scope — a lower index is stricter. As a fossil-fuel-free community, new construction in Concord must be built all-electric, so the all-electric columns apply.
| Project type | Mixed-fuel | Mixed-fuel + solar | All-electric | All-electric + solar |
|---|---|---|---|---|
| New construction | HERS 42 | 42 | 45 | 45 |
| New construction — embodied-carbon credit | 45 | 45 | 48 | 48 |
| Accessory dwelling unit (ADU) | 52 | 55 | 55 | 58 |
| Major alteration / renovation / change of use | 65 | 70 | 70 | 75 |
A HERS rating is triggered by new construction, additions over 1,000 sq ft (or more than 100% of the existing conditioned area), and Level 3 alterations over 1,000 sq ft affecting more than 50% of the home. New homes must also pass a blower-door test at 3.0 ACH50 and include electrification-ready wiring for heat pumps, EV charging, and solar. We model your Concord project up front so you know the exact target and the fastest path to hit it — call (617) 501-6788.
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Certified HERS ratings, blower door testing and energy code compliance across all 351 Massachusetts cities and towns.
