The drafty building and the rats
Why energy retrofits belong in the urban rodent toolbox
Every city has a building that gives itself away.
Not dramatically, just in the way the hallway never quite warms up, or how the front door needs a hip‑check to latch. Tenants mention drafts. The manager mentions heating bills. Someone else mentions the rats. And suddenly the pattern comes into focus.
A door that does not close flush.
A pipe chase with daylight around the edges.
A basement window that rattles in its frame.
A patch job that “worked for a while.”
On paper, the rodent plan looks familiar: sanitation, storage, devices, monitoring. The usual approach.
But the building keeps leaking, not just air, but access.
And that part is often treated as “maintenance” instead of “rodent control,” even though it may be one of the most durable forms of prevention a city can buy.
A recent open‑access study by Gadsden et al. (2024), published in Environmental Research Letters, examined this idea directly. Their question was simple: if more homes become truly energy efficient, meaning sealed, insulated, and harder to enter, do urban rat populations decline over time?
Energy efficiency here does not mean appliances
When most people hear “energy efficiency,” they picture furnaces, thermostats, or rebates.
This research focuses on something more basic and far more relevant to rats: the building envelope.
Doors and door sweeps
Windows and frames
Foundations and exterior walls
Insulation and sealed cavities
Openings around pipes, conduits, vents, and utility penetrations
In the study, an “energy‑efficient home” is essentially a home that is harder for wildlife to enter and use. Retrofitting, in this context, is envelope repair that improves efficiency and, when done well, reduces access.
That maps cleanly to what PMPs see every day. Rats take the same routes that air takes.
What the researchers tested
Because long, controlled field trials inside occupied homes are nearly impossible, the team used an agent‑based model. It simulated brown rats and one natural predator, red foxes, moving through patches of housing, commercial areas, roads, and greenspace.
They built three neighborhood “cityscapes” using Philadelphia as the case study. The neighborhoods differ in density, greenspace, commercial activity, and housing stock, which allowed the model to test how different built environments respond to the same interventions.
Then they ran scenarios over 1, 5, and 10 years:
neighborhoods starting with different proportions of efficient homes (25 percent, 50 percent, 75 percent, up to fully efficient),
retrofitting turned on or off, and
different retrofit durations and rollout patterns.
This is not a claim that weatherization eliminates rats. It is a way to explore how the system behaves when the housing layer changes.
What they found
Three results matter for field teams and city partners.
1) Better starting housing conditions helped.
Neighborhoods that began with a higher share of efficient housing produced lower rat populations over time.
That is the prevention message: baseline housing integrity matters.
2) Retrofitting reduced rats, but not identically everywhere.
Some modeled neighborhoods showed strong rat‑reduction effects from retrofitting. Others showed weaker effects under the same rollout pace.
The implication is that the built environment and resource patterns, such as density, commercial food, and greenspace, shape how strongly housing upgrades translate into population reduction.
3) Big pushes beat slow drips.
Large‑scale initiatives, where many homes become efficient together, showed greater potential for reducing rats than scattered, one‑home‑at‑a‑time upgrades.
If the goal is to shift carrying capacity at neighborhood scale, pace matters.
The model did not drive rats to zero. It also does not capture every real‑world driver, and the authors note that sanitation is underrepresented. But it supports a practical point: structural investments can shift the long‑term baseline, especially when paired with the rest of IPM.
The uncomfortable operational truth: “retrofit” does not automatically mean “rodent‑proof”
The study also highlights a risk PMPs already know well.
Many energy retrofits are designed for energy performance, not wildlife exclusion. Materials and methods are not always chosen or inspected with rodent entry in mind. Sometimes only part of the building’s inefficiencies are addressed. Sometimes work creates new gaps.
So the real question is not “Should cities retrofit?”
It is: Can retrofit programs adopt standards that are explicitly rodent‑aware?
If they can, the payoff may be bigger than comfort and energy savings. It could mean fewer infestations, fewer callbacks, and less reliance on toxic tools.
What this changes for PMPs, property teams, and agencies
This research does not replace field knowledge. It validates something the field has been saying quietly for a long time:
Some “rat problems” are really “building problems.”
If your team is working a chronic building, two early questions matter:
Where is the building leaking access?
Is anyone already planning envelope work, such as doors, windows, siding, roof, or foundation repairs?
When the answer is yes, rodent work becomes easier to stick, but only if the retrofit quality is real.
For PMPs and field teams
Log envelope issues in a structured way, not only in free text.
Examples include missing sweeps, gaps at utility penetrations, broken basement windows, crawlspace access points, and unsealed vents.
When maintenance work is scheduled, ask for the scope and timing. Plan monitoring before and after.
Treat major envelope changes as a phase shift in the account, not background noise.
For property teams
If you are already spending on windows, doors, siding, roof, or entry upgrades, add rodent‑aware specifications up front.
Require sign‑off that penetrations and lower‑level access points were sealed with durable materials.
For agencies and program operators
If you run weatherization, housing rehab, or healthy‑homes programs, consider adding a small rodent‑aware checklist and outcome tracking.
Not “did you see a rat this week,” but consistent measures that show whether the baseline shifts over months and seasons.
None of this requires turning housing staff into pest experts or PMPs into home inspectors. It requires a shared language and a shared log.
Where EUREKA fits
The gap is not only tools. It is data.
Housing programs track energy outcomes.
PMPs track service outcomes.
Public health tracks complaints and risk indicators.
These datasets rarely connect in a way that allows a city to say:
what changed in the building shell,
where it changed,
and what happened to rodent pressure afterward.
That is exactly the kind of connection the EUREKA team is designed to build, turning routine field observations and routine building changes into structured information that cities can learn from.
Closing
Some of the best “rodent prevention” work looks like boring construction.
A door sweep installed correctly.
A foundation gap sealed the right way.
A retrofit done with materials that do not become entry points six months later.
Comfort, energy, and rodent control are not separate stories in many neighborhoods. They are the same story told with different metrics.
The Gadsden et al. (2024) study gives the field a useful systems hypothesis: when building envelopes improve at scale, rat pressure can drop, and the long‑term baseline can move.
For the deeper technical summary, and how this fits into a broader wicked‑problem framework, see the companion pillar article on the EUREKA site.
Source
Gadsden, G., Ferraro, K., Harris, N, 2024. Energy efficient homes for rodent control across cityscapes. Environmental Research Letters 19: 084027.