Massachusetts Cannabis Cultivation Energy: Lighting Caps, Winter Heat Loss, and Eversource G-2 Demand
A Massachusetts indoor grow is a flat lighting block with six months of envelope heat loss on top. Statewide normals run to 6,132 heating degree days and 516 cooling degree days, so winter HVAC and dehumidification dominate the annual kWh budget while humid summers set the July peak. Eversource G-2 and National Grid G-3 bill distribution and transmission demand per kW, and 935 CMR 500.120 caps horticultural lighting power density at 36 watts per square foot unless fixtures beat DLC minimum efficacy by 15 percent.
Massachusetts figures last verified 2026-09-11. Full citations in the Sources section.
What an indoor grow looks like to Eversource or National Grid
A utility does not see plants. It sees a meter that draws a nearly flat block of power when the lights are on, a smaller block when they are off, and a winter envelope load that runs longer than in southern states because Massachusetts averages 6,132 heating degree days and only 516 cooling degree days [noaa-cag-massachusetts]. Summer adds a humid bump when chillers and dehumidifiers work hardest from late June through early September [noaa-cag-massachusetts].
The regulatory layer is specific to Massachusetts. 935 CMR 500.120 caps horticultural lighting power density at 36 watts per square foot of canopy (50 W/sq ft for Tier 1 and Tier 2) unless every fixture beats the DesignLights Consortium minimum efficacy by 15 percent [ma-935-cmr-500-120]. That cap shapes fixture selection before you ever negotiate supply.
Load components in a Massachusetts climate
| Load | Seasonal pattern | Notes |
|---|---|---|
| Horticultural lighting | Flat when lights on | Capped at 36 W/sq ft canopy under 935 CMR 500.120 [ma-935-cmr-500-120] |
| HVAC sensible | Peaks winter and summer | 6,132 HDD drives envelope heat loss [noaa-cag-massachusetts] |
| Dehumidification | Peaks humid summer | Dew points mid-60s to low-70s F coastal [noaa-cag-massachusetts] |
| CO2 enrichment | Follows light cycle | Minor share of total kWh but runs with fans |
| Irrigation pumps | Steady | Usually sub-metered separately in large facilities |
Lighting is the largest single block, but in Massachusetts the annual kWh split tilts toward HVAC and dehumidification compared with drier western states because heating degree days outnumber cooling degree days by more than ten to one [noaa-cag-massachusetts].
Which delivery class a grow lands on
On Eversource Eastern Massachusetts, G-1 Small General Service applies when average demand over 12 months does not exceed 100 kW [eversource-ema-rates-2026]. G-2 Medium General Service covers accounts above 100 kW average with service under 14 kV and bills $20.21/kW distribution demand plus $13.74/kW transmission demand as of September 1, 2026 [eversource-ema-rates-2026]. G-3 Large General Service applies at 14 kV and above [eversource-ema-rates-2026].
National Grid splits differently. G-1 has no demand charge for accounts below 10,000 kWh per month or 200 kW [national-grid-ma-rates]. G-2 General Service (Demand) bills $15.06/kW distribution demand above 10,000 kWh per month with demand not exceeding 200 kW [national-grid-ma-rates]. G-3 Time-of-Use applies above 200 kW with peak hours 8 a.m. to 9 p.m. weekdays, billing $10.48/kW distribution and $21.91/kW transmission [national-grid-ma-rates].
Class assignment on Eversource uses the average of 12 consecutive months of demand rather than a single-month ratchet [eversource-ema-rates-2026]. That gives some relief after a bad summer peak month, but a facility that stays above 100 kW average will sit on G-2 for the year.
Worked example: 15,000 sq ft flowering canopy
Assume a 15,000 sq ft flowering canopy under LED fixtures at 32 W/sq ft installed power (below the 36 W/sq ft regulatory cap) [ma-935-cmr-500-120]. Assume lights run 12 hours per day, HVAC and dehumidification add 35 percent to lighting kWh in this climate, and the facility averages 180 kW peak demand on Eversource G-2.
| Input | Value |
|---|---|
| Lighting installed load | 15,000 sq ft x 32 W/sq ft = 480 kW nameplate |
| Assumed average demand with HVAC | 180 kW (input, not measured) |
| Annual kWh | Assume 2.8 million kWh (input) |
| Supply rate | Massachusetts commercial average 24.52 cents/kWh [eia-epm-5-6-a] |
| Eversource G-2 demand | $20.21/kW distribution + $13.74/kW transmission [eversource-ema-rates-2026] |
Energy cost (supply + delivery energy, simplified): 2,800,000 kWh x $0.2452 = $686,560 per year (using EIA average as a sanity check, not a tariff quote).
Demand cost (delivery only, one month illustrative): 180 kW x ($20.21 + $13.74)/kW = $6,111 per month, or about $73,332 per year if peak holds every month (input assumption).
Real bills add customer charges, riders, Basic Service or supplier supply, and seasonal variation. The point is that at Massachusetts rates, demand charges on G-2 can rival energy cost for a mid-size grow. That is why demand charges and supply choice both matter.
Supply choice and Basic Service
Medium and large commercial customers on Basic Service receive monthly pricing procured quarterly [ma-dpu-basic-service]. A grow that never signs a competitive supply contract sees ISO-NE wholesale volatility pass straight through. Fixed or block-and-index supplier contracts hedge that exposure; compare against trailing Basic Service cost, not a brochure rate.
Efficiency and compliance paths
Mass Save covers lighting and controls, HVAC, custom incentives, and ConnectedSolutions demand response [masssave-business-rebates]. A cultivator meeting the 80 percent on-site renewable threshold can be exempt from the 935 CMR 500.120 lighting and HVAC sizing requirements [ma-935-cmr-500-120]. Every renewal must include a 12-month energy and water usage report regardless [ma-935-cmr-500-120].
Tier 1 and Tier 2 lighting allowances
935 CMR 500.120 allows 50 watts per square foot of canopy for Tier 1 and Tier 2 cultivators versus 36 watts for other tiers [ma-935-cmr-500-120]. Tier status affects both compliance and heat load into HVAC [ma-935-cmr-500-120]. DLC fixtures beating minimum efficacy by fifteen percent are an alternative compliance path [ma-935-cmr-500-120].
Renewable exemption path
Indoor cultivators sourcing eighty percent or more of annual on-site energy from renewables with retired RECs or AECs may be exempt from 935 CMR 500.120 lighting and HVAC requirements [ma-935-cmr-500-120]. SMART 3.0 and onsite generation interact with supply contracts and net metering riders [ma-doer-smart]. Plan legal review before relying on the exemption [ma-935-cmr-500-120].
Twelve-month averaging on Eversource class assignment
Eversource G-1 uses the average of twelve consecutive months of demand rather than a single-month ratchet [eversource-ema-rates-2026]. Expansion projects that spike one month may not move class immediately [eversource-ema-rates-2026]. National Grid G-2 triggers above 10,000 kWh per month with demand not exceeding 200 kW [national-grid-ma-rates]. Site selection between utilities should compare total demand dollars [national-grid-ma-rates] [eversource-ema-rates-2026].
Cultivation licensing freeze and retrofit focus
Commissioners voted for a temporary freeze on new cultivation licenses effective June 16, 2026 [ma-ccc-modernizing-act-2026]. Licensed canopy capacity was 4.57 million square feet as of December 2025 [ma-ccc-10b-sales-2026]. Energy retrofits on existing canopy dominate new construction for supply procurement [ma-ccc-modernizing-act-2026].
ConnectedSolutions revenue alongside supply
Mass Save ConnectedSolutions pays C and I customers to curtail or dispatch storage during ISO-NE peak events [masssave-business-rebates]. Cultivation sites with flexible HVAC may capture revenue without cutting flower-room lighting [masssave-business-rebates]. Enrollment is separate from supplier choice [masssave-business-rebates].
Annual energy and water reporting at renewal
Every cultivator renewal must include a twelve-month energy and water usage report under 935 CMR 500.120 [ma-935-cmr-500-120]. Use the same interval export prepared for supplier negotiations [ma-935-cmr-500-120]. HVAC and dehumidification systems require Massachusetts-licensed mechanical engineer certification [ma-935-cmr-500-120].
DLC fifteen percent efficacy alternative
Fixtures on the DesignLights Consortium horticultural QPL that beat DLC minimum efficacy by at least fifteen percent satisfy lighting rules as an alternative to the 36 W/sq ft cap [ma-935-cmr-500-120]. Document QPL listing numbers in compliance files [ma-935-cmr-500-120].
Additional procurement and tariff notes
SMART 3.0 applications opened October 15, 2025 for behind-the-meter solar [ma-doer-smart]. Eighty percent renewable on-site may exempt lighting and HVAC rules [ma-935-cmr-500-120].
Additional load and utility notes
Eversource class assignment uses twelve-month average demand [eversource-ema-rates-2026]. National Grid G-3 TOU peak is 8 a.m. to 9 p.m. weekdays [national-grid-ma-rates].
Additional load and utility notes
June 16, 2026 cultivation licensing freeze limits new canopy meters [ma-ccc-modernizing-act-2026]. Retrofits on 4.57 million square feet of licensed canopy dominate spend [ma-ccc-10b-sales-2026].
Renewal reporting and engineer certification
Every cultivator renewal includes twelve-month energy and water usage under 935 CMR 500.120 [ma-935-cmr-500-120]. HVAC and dehumidification require Massachusetts-licensed mechanical engineer certification [ma-935-cmr-500-120]. ConnectedSolutions may add revenue without cutting flower lighting [masssave-business-rebates].
36 W/sq ft compliance and heat load
935 CMR 500.120 limits lighting to 36 W/sq ft except Tier 1 and 2 at 50 W/sq ft [ma-935-cmr-500-120]. Compliance caps sensible heat into HVAC [ma-935-cmr-500-120]. SMART 3.0 rooftop solar may support eighty percent renewable exemption [ma-doer-smart] [ma-935-cmr-500-120]. Twelve-month average demand sets Eversource class [eversource-ema-rates-2026].
Supplemental tariff and procurement detail
ConnectedSolutions may pay curtailing HVAC without dark flower rooms [masssave-business-rebates]. June 2026 cultivation freeze concentrates retrofits on licensed canopy [ma-ccc-modernizing-act-2026]. Twelve-month energy and water report due each renewal [ma-935-cmr-500-120].
Freeze-era canopy retrofits
June 16, 2026 cultivation licensing freeze focuses energy spend on 4.57 million square feet of licensed canopy [ma-ccc-modernizing-act-2026]. ConnectedSolutions and SMART 3.0 stack with supply choice [masssave-business-rebates] [ma-doer-smart].
Renewal reporting discipline
Twelve-month energy and water usage reports are due each cultivator renewal [ma-935-cmr-500-120]. Engineer-certified HVAC sizing is required [ma-935-cmr-500-120].
SMART 3.0 application timing
File SMART 3.0 applications before major rooftop solar capex [ma-doer-smart].
Renewal reporting and HVAC certification
Marijuana cultivators must submit twelve-month energy and water usage reports at each license renewal under 935 CMR 500.120 [ma-935-cmr-500-120]. Engineer-certified HVAC sizing is required before the Commission approves canopy changes [ma-935-cmr-500-120]. SMART 3.0 applications should be filed before major rooftop solar capex so on-site generation credits stack with supply contracts rather than conflicting with net metering rules [ma-doer-smart]. Canopy licensing is frozen, so existing 4.57 million square feet of canopy concentrates retrofits on meters already energized [ma-ccc-10b-sales-2026].
Related pages
Compare commercial rates across utilities, read the switching guide, or see the Eversource Massachusetts utility page for tariff detail.
Compare with other states
Frequently asked questions
What Eversource class does a mid-sized Massachusetts grow usually land on?
G-1 Small General Service covers demand not exceeding an average of 100 kW over 12 months. G-2 Medium General Service applies above 100 kW average demand with service under 14 kV. G-3 Large General Service applies at 14 kV and above with customer-owned transformers. Class assignment uses the average of 12 consecutive months of demand, not a single-month ratchet.
Does a large Massachusetts grow get a fixed default supply price?
Not by default. Medium and large commercial Basic Service customers receive monthly pricing procured quarterly unless they request a three-month fixed option. A grow that never signs a supplier contract rides ISO-NE wholesale volatility through Basic Service.
How does Massachusetts humidity change a grow's demand profile?
Coastal and river-valley sites see summer dew points in the mid-60s to low-70s F from late June through early September. Latent load from plants and humid outdoor air peaks in summer, and dehumidification often sets the monthly peak even when lighting load is flat.
What does 935 CMR 500.120 require for lighting?
Horticultural lighting power density must stay at or below 36 watts per square foot of canopy, or 50 W/sq ft for Tier 1 and Tier 2, unless fixtures are on the DLC horticultural QPL and beat the minimum efficacy by at least 15 percent. Cultivators sourcing 80 percent or more of on-site energy from renewables can be exempt.
Are there Massachusetts rebates for grow HVAC or dehumidifiers?
Mass Save offers HVAC, custom incentives, and building controls for C&I customers. There is no prescriptive horticultural LED measure listed, but custom and deep retrofit paths may apply. Confirm eligibility before purchasing.
Why does the 2026 cultivation licensing freeze matter for energy?
The Commission voted for a temporary freeze on new cultivation licenses effective June 16, 2026, against 4.57 million square feet of licensed canopy. Existing cultivators' energy costs and retrofit decisions, not new buildouts, are the near-term market.
Related reading
- Massachusetts Cannabis Energy: Electricity Choice, ISO-NE Rates, and CCC Licensing for Licensed Operators
Massachusetts cannabis power: DPU choice on Eversource and National Grid, Basic Service benchmarks, and 24.52 cents/kWh commercial average.
- Massachusetts Commercial Electricity Rates for Cannabis Facilities: Basic Service, ISO-NE, and Utility Classes
Massachusetts commercial power at 24.52 cents/kWh vs. the U.S. average, Eversource and National Grid G-1/G-2/G-3 demand charges, and Basic Service tiers.
- How to Switch Electricity Suppliers in Massachusetts: A Step-by-Step Guide for Cannabis Businesses
Step-by-step Massachusetts supplier switching for cannabis on Eversource, National Grid, and Unitil: Basic Service benchmarks, DPU rules, and enrollment timing.
- Eversource Massachusetts for Cannabis Facilities: G-1, G-2, G-3, Basic Service, and Mass Save
Eversource Massachusetts cannabis billing: Eastern and Western MA G-1/G-2/G-3 classes, demand charges, Basic Service tiers, and competitive supply enrollment.
- Connecticut Cannabis Cultivation Energy: Manufacturer Rate Classes, Summer Humidity, and Standard Service
Connecticut indoor grow power: humid summers, Eversource Rate 56/58 demand, 500 kW LRS threshold, and a worked cost example at 19.62 cents/kWh.
- Rhode Island Cannabis Cultivation Energy: Warwick Industrial Loads, G-02 Demand, and LRS Winter Swings
RI indoor grow power: Warwick cultivators, G-02 vs G-32 classes, and Last Resort Service summer-winter price swing.
- Demand Charges Explained for Cannabis Cultivators
What a demand charge is, how utilities measure peak kW in 15- or 30-minute windows, why grow rooms get hit hard, how ratchets work, and a worked example.
- Dehumidification Load in Indoor Cannabis Cultivation
How much water a flowering canopy puts into the air, latent vs sensible load, dehumidifier pints-per-kWh ratings, and how it shows up on the electric bill.
- LED vs. HPS Grow Lighting: Energy Cost Comparison
Cited efficacy for double-ended HPS and DLC-listed LEDs, the heat-load difference, a worked cost comparison per 1,000 sq ft, and how rebates change payback.
- HVAC Sizing for Cannabis Grow Rooms
How to turn lighting watts into cooling tons, why latent load is half the problem in a flower room, what oversizing costs, and how HVAC drives demand charges.
Jason Taken founded Jaken Energy, the commercial energy procurement practice behind this site. He works with licensed cannabis operators in deregulated electricity markets to lower supply rates, manage demand charges, and evaluate efficiency upgrades.
Sources
Inline citations in this article, such as [eia-epm-5-6-a], refer to the entries below. Links open the primary source in a new tab.
- [eia-epm-5-6-a]Electric Power Monthly, Table 5.6.A: Average Price of Electricity to Ultimate Customers by End-Use Sector, by State, June 2026 and June 2025 — U.S. Energy Information Administration. Accessed 2026-09-11.
- [ma-935-cmr-500-120]935 CMR 500.120: Additional Operational Requirements for Marijuana Cultivators (energy and environmental standards) — Massachusetts Cannabis Control Commission (via Cornell LII). Accessed 2026-09-11.
- [eversource-ema-rates-2026]2026 Summary of Eastern Massachusetts Electric Rates for Greater Boston Service Area, rates effective September 1, 2026 — Eversource Energy. Accessed 2026-09-11.
- [national-grid-ma-rates]Massachusetts Business Service Rates (G-1, G-2, G-3) — National Grid. Accessed 2026-09-11.
- [noaa-cag-massachusetts]Climate at a Glance: Massachusetts statewide heating and cooling degree days, 1991-2020 base period averages — NOAA National Centers for Environmental Information. Accessed 2026-09-11.
- [ma-dpu-basic-service]Basic service information and rates (updated July 6, 2026) — Massachusetts Department of Public Utilities. Accessed 2026-09-11.
- [masssave-business-rebates]Mass Save Business Rebates and Incentives — Mass Save. Accessed 2026-09-11.
- [ma-doer-smart]Solar Massachusetts Renewable Target (SMART) Program details — Massachusetts Department of Energy Resources. Accessed 2026-09-11.