London households have entered the summer facing another sharp increase in energy costs, but the same 13% rise will not be experienced uniformly across the UK.
Ofgem raised its energy price cap on July 1, taking the annualised figure for a typical dual-fuel household paying by direct debit from £1,641 to £1,862. The new cap remains in force until September 30 and applies to households on default tariffs in England, Scotland and Wales.
For Londoners already contending with high rents, mortgage payments and general living costs, the £221 increase represents another squeeze on household budgets. Yet the headline figure does not mean every property will receive a bill for £1,862, nor does it cover every part of the UK.
The cap limits the rates suppliers can charge for each unit of gas and electricity, along with daily standing charges. The final amount paid still depends on how much energy a household uses.
It also does not apply in Northern Ireland, which has a separate regulator, a different tariff system and a domestic heating market that remains heavily dependent on oil.
London households face higher unit costs
The July increase reverses the 7% reduction introduced in April and means London households on standard variable tariffs will pay more for every unit of gas or electricity they consume.
That may be particularly difficult for residents of older or inefficient properties.
London’s housing stock includes Victorian terraces, subdivided townhouses, converted flats, postwar estates and modern apartment developments. Two homes on the same street can have substantially different heating requirements depending on insulation, glazing, exposure, floor area and how the property has been altered over time.
A recently built flat surrounded by other occupied properties may retain heat relatively well. A top-floor conversion in an older building, by comparison, may lose heat through its roof, windows and external walls even when both homes use similar boilers and thermostats.
The price cap cannot account for those differences. It controls the rate charged for energy, not the amount required to heat a particular home.
Private tenants may also have limited control over the condition of the boiler, radiators or insulation. While an owner-occupier can consider replacing an ageing heating system, tenants generally depend on landlords or managing agents to authorise significant work.
In apartment blocks with communal heating arrangements, residents may not be protected by the domestic price cap in exactly the same way as households with individual gas and electricity accounts.
A price cap is not a cap on the bill
The £1,862 figure is based on typical annual consumption and should not be interpreted as a maximum bill.
A household using more gas and electricity than Ofgem’s model will pay more. A household using less will pay less.
That distinction matters because rising unit prices make existing inefficiencies more expensive. A heating system that wastes energy through poor controls, uneven circulation or unsuitable settings may have been tolerated when prices were lower, but each avoidable unit of consumption now carries a greater cost.
Some residents respond to higher bills by reducing the number of hours their heating runs. Others lower their thermostat or heat only selected rooms.
Those steps can reduce consumption, but they do not address faults or design problems within the heating system itself. A boiler may be working correctly while the radiators remain poorly balanced, the controls are outdated or the property loses heat almost as quickly as it is produced.
Conversely, a high bill does not automatically prove that a boiler needs to be replaced.
Northern Ireland follows a different system
The comparison becomes more complicated beyond Great Britain.
Northern Ireland is not covered by Ofgem’s domestic price cap. Its electricity and regulated gas tariffs are overseen by the Utility Regulator, which conducts separate reviews of suppliers operating within the region.
Changes introduced there on July 1 included a 6.2% increase in Power NI’s regulated domestic electricity tariff and a 15.7% increase in Firmus Energy’s regulated gas tariff in its Ten Towns network.
Those figures cannot be compared directly with Ofgem’s 13% headline increase because the markets, suppliers and typical-consumption calculations are different.
The way homes are heated also differs significantly.
Official Northern Ireland statistics show that oil central heating remained the primary heating source for 61% of households in 2024/25. Although that proportion has fallen from 70% in 2015/16, heating oil remains far more prominent than it is in London.
Many Northern Irish households therefore experience rising heating costs through changes in the price of oil purchased directly from suppliers, rather than through an Ofgem-regulated gas tariff.
That makes the phrase “UK energy prices” deceptively simple. A London flat using mains gas, a Belfast house with an oil-fired boiler and a rural property relying on oil and electricity can all experience the same movement in wholesale energy costs differently.
Different markets, similar problems inside the home
While the regulatory and fuel markets differ, many of the physical causes of wasted household heat are much the same.
According to Mark Gunda from JobDoneNI.com, a boiler installation specialist based in Northern Ireland, households should distinguish between the price of energy and the efficiency with which their heating system uses it.
“The tariff structures are different, particularly for Northern Ireland households that rely on heating oil, but the engineering principles inside the property don’t change,” Gunda said.
“A boiler has to work as part of a complete system. Its size, the condition of the pipework, the radiator capacity, the controls and the hot-water demand all affect how efficiently the home is heated. Replacing the appliance without assessing those other elements can mean the homeowner never receives the improvement they expected.”
Modern condensing boilers are designed to recover heat that older appliances would have lost through the flue. Their real-world performance, however, can depend on factors such as system temperature, boiler modulation, radiator sizing and the way the controls have been configured.
An appliance carrying a high efficiency rating can still operate within a poorly designed or badly maintained central-heating system.
When an older boiler becomes more expensive to keep
Rising energy prices often renew the debate over whether an older boiler should be repaired or replaced.
Age matters, but it is not the only consideration. A well-maintained boiler that can still be repaired economically may remain serviceable, particularly if the wider system is in good condition. Repeated breakdowns, unavailable components, corrosion or persistent pressure problems can change that calculation.
Older non-condensing boilers may also consume more fuel to deliver the same useful heat as modern equipment, although household savings will vary according to the property, controls, existing appliance and occupant behaviour.
Gunda said homeowners should be wary of choosing a replacement purely according to the output of the old boiler or the number of bedrooms in the property.
“Bigger is not automatically better,” he said. “An oversized boiler can cycle on and off repeatedly rather than operating steadily, which can increase wear and prevent it from working as efficiently as intended.
“A professional assessment should consider the building’s heat loss and hot-water requirements, as well as the existing radiators and pipework. The correct replacement is the one that suits the home, not necessarily the most powerful unit available.”
Professional competence is also a legal and safety issue. In Northern Ireland, anyone installing, repairing or maintaining domestic gas appliances must be registered with Gas Safe and hold the qualifications required for the work being undertaken. Oil-fired boiler installations should be carried out by an appropriately trained technician, with NI Direct recommending the use of an OFTEC-registered professional.
Simple warning signs should not be ignored
Not every heating problem requires a new boiler, but households can look for signs that the system needs professional attention.
Radiators that remain cold at the bottom may indicate restricted circulation or a build-up of material within the system. Large differences in temperature between rooms can point to poor balancing, unsuitable radiator sizing or problems with individual valves.
Repeated pressure loss should also be investigated rather than continually corrected by topping up the system. Unusual noises, recurring fault codes, water leaks or a boiler that switches on and off at short intervals may indicate a developing problem.
Residents should not attempt to open, modify or repair gas appliances themselves.
The Gas Safe Register advises that gas work should be completed by a registered engineer, while boilers and other appliances should be maintained regularly. Carbon monoxide alarms provide an additional safeguard but do not replace professional installation and servicing.
Summer can be a practical time to test the heating briefly and arrange work, before colder weather produces the seasonal surge in breakdowns and callouts.
London’s challenge goes beyond the price cap
The latest increase will draw understandable attention to Ofgem, suppliers and wholesale markets, but London’s household energy problem cannot be reduced to a single regulated figure.
The capital combines expensive energy with some of the country’s highest housing costs and an unusually varied building stock. Many residents live in properties whose heating systems have been extended, altered or partially upgraded over several decades.
A new boiler cannot compensate fully for severe heat loss through the building itself. Equally, insulation improvements will not resolve a defective appliance, poor circulation or unsuitable controls.
The greatest savings are often achieved by treating the home as a complete system, considering the building fabric, boiler, radiators, pipework and household routines together.
London and Northern Ireland may sit within different energy markets, with different regulators and sharply different patterns of fuel use. The underlying calculation for households is nevertheless similar.
They cannot control wholesale prices or regulatory decisions, but they can establish whether the energy they purchase is being converted into useful heat as effectively as possible.
With the price cap now 13% higher, inefficiencies that once went unnoticed may become increasingly difficult to ignore.
