Why is my house so cold?
It is one of the most common questions we are asked, and the honest answer is: it depends on your building. A cold home is a symptom, not a diagnosis. The heat is escaping somewhere — but until you measure where, spending money on a fix is guesswork. Two houses that feel equally cold can have completely different causes, and therefore need completely different solutions.
Homeowners usually assume the answer is more insulation. Sometimes it is. But just as often the real culprit is air leakage, poor windows, thermal bridging, an unbalanced ventilation system or cold suspended floors — none of which extra loft insulation will fix. That is why so many people insulate, and still feel cold.
Where heat actually escapes
Heat leaves a building in several ways at once, and the balance is different in every home. A proper investigation looks at all of them together.
Air leakage
Uncontrolled air movement carries heat straight out of the building — and pulls cold air in. In many older London homes this is the single largest source of wasted heat, and it is completely invisible without testing.
Missing or under-performing insulation
Insulation that is thin, patchy, poorly fitted or missing altogether leaves whole areas of wall, roof or floor losing heat far faster than they should. Thermal imaging shows exactly where the gaps are.
Thermal bridges
A thermal bridge is a path through the fabric where heat escapes more easily — a concrete lintel, a steel beam, a wall-to-floor junction. These cold spots not only waste heat but often become the first place condensation and mould appear.
Windows and glazing
Poorly performing or badly fitted windows lose heat both through the glass and around the frame. The fix is not always replacement — sometimes it is sealing and upgrading what you have.
Cold suspended floors
Ventilated timber ground floors lose heat downwards and let cold air up between the boards. Cold feet are often the most obvious sign of an uninsulated, leaky floor.
Unbalanced ventilation
Ventilation is essential for a healthy home, but poorly designed extract or leakage can dump warm air outside far faster than needed. Getting the balance right keeps you warm and the air fresh.
Why an EPC is not enough
An Energy Performance Certificate is a useful headline, but it is a modelled estimate, not a measurement. It is produced from standard assumptions about your property type — it does not inspect your actual walls, test your actual airtightness, or locate a single real defect. Two identical-looking homes can have the same EPC rating and behave completely differently in practice.
An EPC will never tell you that the reason your back bedroom is freezing is a thermal bridge behind the wardrobe, or that half your heat is leaking through an unsealed floor. Only a measured investigation of your specific building can do that.
How Retrofit IQ investigates heat loss
A Cold Home & Heat Loss Investigation is a measured, whole-building diagnosis. We use the right combination of methods for your property — not a single test in isolation.
Thermal imaging
Carried out in valid conditions, a calibrated thermal survey reveals missing insulation, thermal bridges and cold spots across walls, ceilings and floors — the patterns of heat loss made visible.
Blower door testing
We measure your home's air-leakage rate to a recognised standard, quantifying how much heat is being lost to uncontrolled air movement — and, with smoke tracing, showing exactly where.
Moisture and ventilation review
We check humidity, moisture and the ventilation strategy, because heat loss, comfort and condensation are all connected. Fixing one without the others rarely works.
Fabric, loft, window and floor inspection
We inspect the loft, windows, doors and — where accessible — floors and walls, assessing insulation continuity and construction so the thermal findings are interpreted in context.
Insulation failure or air leakage? They are not the same
This distinction matters enormously, and it is where most guesswork goes wrong. Missing insulation and air leakage feel similar — a cold room, a chilly wall — but they are different problems with different fixes. Insulation slows heat conducting through a solid element; airtightness stops heat being carried away by moving air. Add insulation to a leaky house and you may barely notice the difference. Seal a well-insulated but leaky house and it can transform.
Only by measuring both — thermal imaging for the insulation story, the blower door for the air-leakage story — can we tell you which one is actually costing you comfort and money, and therefore what to fix first.
The fabric-first principle: why the order of works matters
There is a right order to improving a cold home, and getting it wrong wastes money. The principle we work to is 'fabric first': before upgrading heating systems or installing renewable technology, you reduce the amount of heat the building loses in the first place. A well-sealed, well-insulated home needs far less energy to stay warm — and every heating system, from a boiler to a heat pump, then works better and costs less to run.
Fabric-first also has an internal order. Air leakage and insulation continuity usually come before window replacement or renewable heating, because they are often cheaper and deliver more comfort per pound. A heat loss investigation establishes that order for your specific home, so you are never persuaded into an expensive measure that should have come later — or one that will not pay back at all.
This matters because improvements interact. Insulate without addressing air leakage and you may be disappointed. Install a heat pump onto a leaky, poorly insulated fabric and you get an oversized, expensive system that struggles to keep you warm. Sequenced correctly, each measure makes the next one work harder. That sequence is one of the most valuable things your investigation delivers.
Cold homes, heat loss and heat pumps
If you are considering an air source heat pump, a heat loss investigation is one of the most valuable steps you can take beforehand. Heat pumps deliver heat at a lower temperature than a traditional gas boiler, which means they perform best in homes where heat loss is low and well understood. In a leaky, poorly insulated home, a heat pump has to be larger, run harder and cost more — and may still leave rooms feeling cold.
By measuring your real heat loss and air leakage first, we can tell you which fabric improvements to prioritise so that a future heat pump is correctly sized and runs efficiently. This avoids the common and expensive mistake of installing an oversized system onto an untreated building. It is the difference between a heat pump that quietly keeps you warm for less, and one that never quite delivers on its promise.
Comfort is not just about temperature
A home can be at 21 degrees on the thermostat and still feel cold. This surprises people, but it is well understood in building physics. Comfort depends not only on air temperature but on the temperature of the surfaces around you — the walls, floors and windows. Stand next to a large cold window or an uninsulated external wall and your body radiates heat towards it, so you feel cold even though the air is warm.
This is why chasing comfort with the thermostat alone is so expensive and so unsatisfying. Warm the surfaces — by improving insulation and reducing thermal bridging — and you feel comfortable at a lower air temperature, which also lowers your bills. A heat loss investigation identifies exactly which cold surfaces are undermining your comfort, so the fix targets how the home actually feels, not just what the thermostat reads.
What a typical cold-home investigation finds
No two homes are the same, but certain patterns recur often enough to be worth describing. In many older London properties, we find that a significant share of heat loss comes from uncontrolled air leakage — through suspended floors, unsealed loft hatches, service penetrations and window reveals — rather than from the walls themselves. Homeowners are frequently surprised, having assumed insulation was their main problem.
We also commonly find thermal bridges at junctions — where floors meet external walls, at window and door reveals, and around structural elements like lintels and beams — that create cold spots and often the first signs of condensation. Missing or poorly fitted insulation in lofts, extensions and behind dry-lined walls is another regular finding. The point of the investigation is that we do not assume any of this: we locate and measure what is actually happening in your home, then tell you which findings matter most.
Part of a full Building Performance Investigation
A heat loss investigation is a core part of our Building Performance Investigation — the whole-building service that ties air leakage, insulation, thermal bridging, moisture and ventilation into one coherent diagnosis and a single prioritised plan. If your home is cold, this is almost always the most valuable next step, particularly before a heat pump or major refurbishment.
What you receive
- A clear diagnosis of where your home loses heat and why
- Thermal images and photographic evidence throughout
- A measured air-leakage result where blower door testing is carried out
- Findings prioritised by what matters most to comfort and cost
- A practical, sequenced remedial strategy — fabric first
- Clear next steps you can act on with any competent contractor
A real-world investigation example
A family in a 1930s London semi had spent on top-up loft insulation and thicker curtains, but the house was still cold and expensive to heat. The investigation found the loft was not the problem at all: thermal imaging showed the walls performing reasonably, while the blower door revealed heavy air leakage through the suspended ground floor, the loft hatch and dozens of service penetrations, plus a clear thermal bridge chilling the rear corner. In other words, they had insulated the one element that was already adequate. Sealing the air-leakage paths and addressing the thermal bridge, in that order, made the home noticeably warmer at a lower thermostat setting — a result more insulation alone would never have delivered.
Common homeowner mistakes
The classic error is assuming 'cold house' automatically means 'needs more insulation', and spending accordingly before measuring where the heat actually goes. Another is trusting the EPC — a modelled estimate that inspects nothing — to guide real improvements. The most expensive mistake we see is installing an oversized heat pump onto a leaky, poorly understood fabric, producing a system that runs hard, costs a fortune and still leaves rooms cold. Investigating first, and following a fabric-first order of works, avoids all three.