Tenant Comfort and Energy Efficiency

The call usually comes in January. A landlord phones us and says something like, "My tenants keep complaining that the apartment is cold, but the thermostat is set to 70 and the boiler is running constantly. I just had the boiler serviced. It is working fine. What else can I do?"

This is one of the most common calls we get at Horizon Homes. And the answer is almost never about the heating system. The problem is the building.

A thermostat set to 70 degrees in a poorly insulated apartment does not mean the tenant feels 70 degrees. It means the air near the thermostat is 70 degrees. The walls might be 55 degrees. The floor near exterior walls might be 50. The window seat where someone likes to read in the evening might have a steady stream of cold air flowing down from the window and across their lap. The heating system is working perfectly. The building envelope is failing.

Why "The Heat Is On" Does Not Mean "The Apartment Is Warm"

Understanding why tenants complain about cold even when the heat is running requires a basic understanding of how human comfort works. We do not just feel air temperature. We feel the combined effect of air temperature, surface temperatures, air movement, and humidity.

Mean Radiant Temperature

This is the single most important concept for understanding tenant comfort complaints. Mean radiant temperature (MRT) is the average temperature of all the surfaces in a room - walls, floor, ceiling, windows. Your body constantly exchanges heat with these surfaces through radiation, and if they are cold, you feel cold regardless of what the air temperature is.

In a well-insulated apartment, interior wall surface temperatures stay within 3-5 degrees of the air temperature. In a poorly insulated apartment - especially one with empty wall cavities common in Maine's 1940's and 1950's-era buildings - interior wall surface temperatures can be 10-15 degrees below air temperature during cold weather.

That is why a tenant can be sitting in a room with the thermostat reading 70 and feel genuinely cold. The air is 70, but the walls around them are 55-60 degrees, and their body is radiating heat to those cold surfaces. The perception of cold is real, not imagined.

Cold Air Drafts

Air leakage through the building envelope creates another source of discomfort that has nothing to do with thermostat settings. Cold outdoor air enters through gaps at windows, at the sill plate, around electrical outlets on exterior walls, through plumbing penetrations, and through dozens of other small openings that add up to significant air exchange.

In older multi-unit buildings, the stack effect amplifies this problem. Warm air rises through the building and exits through the upper floors and roof, pulling cold air in at the lower floors. First-floor apartments in Maine triple-deckers are notorious for drafts at floor level - cold air literally being sucked in through the basement and ground-floor openings.

Humidity

Maine winters are dry, and poorly sealed buildings make the problem worse. As warm, relatively moist indoor air escapes through leaks in the envelope, it is replaced by dry outdoor air. The resulting low indoor humidity (often 15-20% in leaky buildings) makes cold feel colder and irritates skin, sinuses, and respiratory systems.

The Real Cost of Tenant Discomfort

Landlords sometimes dismiss comfort complaints as tenant pickiness. But the cost of ignoring these complaints is real and measurable.

Turnover

Uncomfortable tenants leave. They might not cite "cold apartment" as the reason - they will say they found a better place, or they are moving closer to work, or some other socially comfortable excuse. But when we talk to property managers, they consistently report that units with known comfort problems have higher turnover rates.

In the Portland rental market, each turnover event costs $1,500 to $3,000 in lost rent, cleaning, repairs, and re-leasing costs. If poor building performance causes even one additional turnover per year across a multi-unit building, the cost exceeds what most insulation projects would have cost.

Bad Reviews

In the age of online reviews and tenant forums, a cold apartment gets talked about. Prospective tenants check reviews, ask around, and search for address-specific complaints. A reputation for cold units makes it harder to attract quality tenants and puts downward pressure on the rent you can charge.

Heating System Wear

When a heating system runs constantly because the building cannot retain heat, the equipment wears out faster. Boiler replacements run $8,000 to $15,000. Extending a boiler's useful life by even two or three years through better insulation more than justifies the envelope investment.

Maintenance Calls

Cold-related maintenance issues - frozen pipes, ice dams, condensation damage, mold growth in cold corners - are all symptoms of building envelope problems. Each call costs time and money, and they cluster during the months when you least want to be dealing with them.

Fixing the Problem - Building Envelope First

The solution to most tenant comfort complaints is not a bigger boiler or more radiators. It is a better building envelope. Here is how we approach comfort problems in rental buildings.

Step 1 - Assessment

A free energy assessment identifies exactly where the building is losing heat and where air is leaking. We use thermal imaging cameras and blower door testing to make invisible problems visible. The assessment typically takes two to three hours for a multi-unit building and gives us the data we need to recommend specific solutions.

Step 2 - Air Sealing

Air sealing is almost always the first priority. We seal the gaps and penetrations where air moves through the building envelope - the attic floor, basement ceiling, sill plate, around plumbing and electrical runs, and at dozens of other common leakage points.

The impact on comfort is often immediate and dramatic. Tenants notice the difference within days. The drafts stop, the rooms feel warmer at the same thermostat setting, and the heating system runs less. For most buildings, air sealing alone reduces heating energy use by 15-25% and makes a significant improvement in comfort.

Air sealing work can typically be done in occupied units with minimal disruption. Most of the work happens in the attic and basement, not in the living spaces.

Step 3 - Insulation

After air sealing, adding insulation addresses the mean radiant temperature problem. When walls, ceilings, and floors are properly insulated, their interior surface temperatures stay close to room temperature, and the radiative heat loss from occupants' bodies drops dramatically.

For walls, we blow dense-pack cellulose into wall cavities through small holes drilled in the exterior siding. This does not require any interior work, which is critical for occupied rental units. The process takes one to two days for a typical three-unit building, and the holes are patched and painted the same day.

For attics, we blow cellulose insulation to R-49 or R-60, which is the current standard for our climate zone. Most older buildings have R-10 to R-19 in the attic - well below what is needed.

For basements, we insulate the basement ceiling or walls depending on building configuration. For rubble-foundation basements and crawl spaces, we subcontract spray foam, which is the most effective approach for those irregular surfaces.

Step 4 - Heating System Optimization

Once the building envelope is addressed, the heating system often needs adjustment. A boiler that was sized for a leaky building is now oversized for a well-insulated one. We can adjust settings or, if the boiler is aging, recommend a right-sized replacement.

For buildings ready for a heating system change, cold-climate heat pumps provide individual zone control for each unit - which is the ultimate solution to tenant comfort because every tenant controls their own temperature. Mitsubishi cold-climate mini-splits are rated to heat effectively down to -13 degrees and also provide cooling in summer.

Efficiency Maine Rebates for Rental Properties

Efficiency Maine provides rebates for insulation, air sealing, and heat pump installations in rental properties. The amounts are income-dependent and vary by project type, but they can cover a meaningful portion of project costs.

We are a Top Efficiency Maine Contractor - a designation we have held for 10+ years - and we handle the entire rebate process. Rebates are applied directly to your invoice, so you never wait for reimbursement.

What Tenants Actually Experience After Upgrades

We hear consistent feedback from tenants in buildings we have upgraded:

• "It is actually warm everywhere now." Not just near the radiator - the whole room feels comfortable
• "My heating bill went down." Typical reductions of 20-40% on tenant-paid heating costs
• "The drafts are gone." The most immediate and noticeable change
• "No more ice on the inside of the windows." Condensation and ice on windows are symptoms of air leakage and poor insulation that disappear after envelope work

For landlords, the feedback translates directly to longer tenancies, fewer complaints, fewer maintenance calls, and the ability to command appropriate rent levels.

Getting Started

If your tenants are complaining about cold - or if you are dealing with the downstream effects of a leaky building like high turnover, maintenance headaches, or below-market rents - the first step is understanding what is actually happening in the building.

Schedule a free energy assessment or call (207) 221-3221. We have been solving comfort problems in Maine rental buildings for 20+ years. We will walk through the building with you, show you exactly where the problems are, and give you a clear plan with costs, rebates, and expected results. There is no obligation - just good information that helps you make a smart decision about your property.