Portable Air Conditioning: Who Is Responsible When It Changes the Way a Home Ventilates?
As we see more periods of extreme summer heat, portable air conditioning is becoming an increasingly common sight in residential properties.
For residents experiencing overheating, it can seem like an obvious solution.
Buy a unit from a well-known retailer, connect the exhaust hose, switch it on and the room gets cooler.
But there is another question that Social Housing Providers should perhaps be asking:
What happens to the ventilation system when a resident introduces a portable air-conditioning unit into the home?
And perhaps an even more important question:
Who is responsible if problems subsequently arise?
The cooling isn’t the whole story
A typical 12,000 BTU portable air conditioner can provide around 3.5 kW of cooling.
That’s a significant amount of cooling and can make a real difference to a hot bedroom or living room.
However, many portable units use a single exhaust hose.
The unit takes air from inside the property, uses it as part of the cooling process and then exhausts that air outside.
That means the air being removed from the home has to be replaced.
Where does that replacement air come from?
It may come through open windows, background ventilation openings or simply through leakage within the building.
The result can be that the air-conditioning unit changes the pressure and airflow conditions within the property.
Consider the difference in airflow
This is where the scale of the issue becomes interesting.
A typical home may have been designed around relatively modest background ventilation requirements.
A portable AC can be moving several times more air than the home’s normal ventilation system.
So while the resident may simply see:
“My air conditioner is cooling my room.”
the building may be experiencing:
“I’m now removing a very large volume of air from the property and drawing replacement air in from somewhere else.”
And if that replacement air is hot outside air, some of the cooling benefit is immediately lost.
What happens to the existing ventilation system?
This is particularly relevant where the property has mechanical ventilation.
The AC doesn’t necessarily make the existing ventilation system “unbalanced” in the traditional sense.
But it can significantly alter the pressure conditions within the dwelling.
That could potentially affect how air enters and leaves the property.
It raises questions that Social Housing Providers should understand:
- Could the AC influence the operation of existing ventilation strategy?
- Could it increase uncontrolled air infiltration?
- Could it reduce the effectiveness of the cooling being provided?
- Could it contribute to comfort or indoor air-quality problems?
- What happens if the resident is using the AC while the mechanical ventilation is operating?
These aren’t necessarily reasons to prevent residents from using portable air conditioning.
But they are reasons to understand the interaction between the two systems.
And then there is the responsibility question.
Imagine a resident purchases a portable air conditioner from a major high-street or online retailer.
They install it in their home in accordance with the manufacturer’s instructions.
They then experience problems with ventilation, condensation, air movement or indoor air quality.
Who is responsible?
The resident could reasonably argue:
“I bought a standard domestic appliance and used it as intended. The ventilation system is provided and maintained by my landlord.”
The landlord, on the other hand, may reasonably say:
“The portable AC was not part of the ventilation system we designed or installed.”
This is where the situation becomes less straightforward.
I don’t think there is a simple answer that says the landlord is automatically responsible.
But I do think Social Housing Providers need to consider whether the use of portable air conditioning is becoming sufficiently common that it should form part of their overheating, ventilation and resident guidance strategies.
This is another example of why the whole dwelling matters.
We often look at ventilation, overheating, damp and mould as separate issues.
They aren’t.
A resident’s attempt to solve overheating can affect ventilation.
Changes to ventilation can affect moisture control.
Changes to moisture control can affect damp and mould risk.
And the building itself determines how all of these things interact.
So perhaps the question isn’t:
“Should residents be allowed to use portable air conditioning?”
Perhaps the better question is:
“Do we understand what happens to our homes when residents do?”
If portable AC is becoming an increasingly important part of the response to overheating, then perhaps housing providers should consider:
What guidance do we give residents?
What does our ventilation strategy say about it?
Do our contractors understand the interaction?
And where does responsibility sit when a resident introduces equipment that wasn’t part of the original building design?
These are questions worth answering before the next heatwave rather than after a complaint.
Because providing a cooling appliance is only part of the solution.
The real challenge is making sure the whole home continues to work as intended.
