You may have seen recent news about an unusually strong El Niño developing across the Pacific Ocean. According to the Met Office, this is predicted to be one of the strongest El Niño event in modern records, with sea temperatures in parts of the equatorial Pacific reaching more than 3°C above average. This extra heat is already influencing weather patterns around the world and is expected to continue doing so through the coming months.
What Is El Niño?
Normally, strong trade winds blow across the Pacific Ocean from South America towards Indonesia. These winds push warm surface water westwards, causing warm seas, frequent rainfall and tropical storms around Indonesia, Papua New Guinea and northern Australia. Meanwhile, cooler water rises to the surface off the west coast of South America.
During an El Niño event, these trade winds weaken and can sometimes partially reverse. Warm water that would normally be piled up around Indonesia drifts back across the Pacific towards South America. This dramatically alters rainfall patterns across the region.
The consequences can be significant. Indonesia and parts of Australia often become much drier than normal, increasing the risk of drought, wildfires and peatland fires. At the same time, parts of western South America can experience intense rainfall and flooding as the warmer ocean fuels stronger storm systems.
What makes El Niño particularly important is that it doesn’t stop at the Pacific. The enormous amount of natural energy being redistributed around the world’s oceans and atmosphere affects weather patterns globally, influencing everything from monsoons in Asia to hurricane activity in the Atlantic and storm tracks across Europe.
What Could It Mean for Britain?
While Britain is a long way from the Pacific, our weather is connected to global climate systems.
Current forecasts suggest El Niño may increase the likelihood of wetter and stormier conditions across the UK during autumn and early winter, particularly across north-west Europe. This does not guarantee flooding or continuous rain, but it does increase the chances of stronger Atlantic weather systems affecting the UK as we move into winter.
While flooding and wildfires often dominate the headlines, one of the biggest global concerns is food production. El Niño can disrupt rainfall patterns across major agricultural regions, affecting crops such as rice, wheat, maize, coffee and palm oil. Drought in parts of South East Asia and Australia, alongside flooding elsewhere, can reduce harvests and increase food prices worldwide. The effects are often felt long after the weather event itself has passed, as global supply chains respond to reduced crop yields. This is one reason meteorologists, governments and commodity markets all pay very close attention when a major El Niño develops.
Why Does This Matter for Heritage Buildings?
For traditional buildings, moisture can be a bigger challenge than temperature.
A wetter and stormier winter can lead to:
Increased driving rain on exposed walls
Higher moisture levels in timber and masonry
Slower drying of traditional building materials
Greater risk of condensation and mould
Increased stress on roofs, gutters and drainage systems from the higher levels of rainfall
Historic buildings are generally very resilient, but they rely on a balance between getting wet and being able to dry out again. Prolonged periods of wet weather can upset that balance and expose maintenance issues that have gone unnoticed during drier seasons.
How Can You Prepare?
A few simple maintenance checks before winter arrives can often prevent much larger problems later:
Clear leaves and debris from gutters and downpipes.
Check gullies and drains are flowing freely.
Inspect roofs for slipped slates, damaged tiles and loose flashings.
Ensure rainwater is discharged away from the building.
Cut back vegetation growing against walls or blocking drainage routes.
Check church towers, parapets and exposed masonry for areas vulnerable to water ingress.
Look for signs of historic leaks in lofts and roof spaces.
Maintain background ventilation to help buildings dry naturally after periods of heavy rain.
Many moisture problems begin with a blocked gutter or a minor roof defect rather than the building fabric itself.
How Woohoo Can Help
At Woohoo, we help building owners understand how their buildings interact with their environment.
Whether it’s a church, listed cottage, farmhouse or commercial property, we look at how heat, moisture and ventilation work together to influence building performance. Through surveys, monitoring and modelling, we can help identify how a building is responding to changing weather patterns and develop practical strategies to improve resilience.
As climate patterns become increasingly unpredictable, understanding how a building behaves in the real world is becoming just as important as improving its energy efficiency.
This winter may provide a fascinating reminder that our historic buildings are not just places we occupy, but sensitive indicators of the changing climate around us.
The traditional answer is simple… when you feel cold.
But some of the most efficient buildings and heating systems don’t wait until occupants reach for a jumper. In fact, many larger buildings and weather-compensated heating systems begin adding small amounts of heat during September or even August to help maintain the heat already stored within the building.
That might sound wasteful, but it is often doing the opposite.
Buildings Are Thermal Batteries
Throughout spring and summer, a building absorbs heat from the sun and surrounding air. Walls, floors and furniture gradually store this energy, much like a battery stores electricity.
As autumn arrives, that stored heat slowly begins to leak away. At first, the losses are small and largely unnoticed. Eventually, however, the building cools enough that occupants start to feel uncomfortable.
For many people, this is the point at which the heating is switched on.
The problem is that the building’s thermal battery is already partly empty and so requires more energy to refill it.
The Cost of Waiting
Most people think heating only warms the air. In reality, a large proportion of the energy is used to warm the building itself.
If a property is allowed to cool significantly, the heating system must warm not only the air but also the walls, floors, ceilings and contents of the building. In heavyweight buildings such as churches, stone cottages and other traditional buildings, this process can take days rather than hours.
Autumn also introduces another challenge: moisture.
As temperatures fall, the air across Britain often becomes cooler and wetter. Internal surfaces become colder, humidity levels rise and condensation becomes more likely. Traditional buildings can also absorb moisture from the environment into the fabric as rainfall increases and drying conditions reduce.
This means that by the time occupants feel cold, the heating system may be trying have two additional tasks.
Re-heating the building fabric
Evaporating the additional moisture that’s been accumulated
Before a damp building can warm up efficiently, some of the heat supplied by the heating system is used to dry surfaces and evaporate moisture from the building fabric. Damp materials also tend to feel colder and conduct heat more readily than dry ones, making the building less comfortable and more expensive to heat.
The Smarter Approach
Many modern weather-compensated heating systems work differently.
Rather than waiting for occupants to become uncomfortable, they monitor outdoor temperatures and gradually add small amounts of heat as autumn progresses. The aim is to slow the building’s heat loss, keep surfaces above condensation temperatures and prevent the thermal battery becoming depleted in the first place.
The result is often:
More stable internal temperatures
Improved comfort
Reduced condensation risk
Drier building fabric
Lower peak heating demand
Less energy spent reheating the building
The heating may run for more days of the year, but often at a much lower output.
An ever increasing number of buildings are heated using Air Source Heat Pumps, they make great use of this early heating as the warmer weather means they can have very high efficiencies and often electricity tariffs can be cheaper in the autumn before the depths of winter when the demand for natural gas greatly increases.
So When Should the Heating Turn On?
There isn’t a specific date. The real question isn’t:
“Am I cold yet?”
Instead, it might be:
“How quickly is my building running out of it’s summer heat?”
For a very lightweight modern home, waiting until October may make little difference. For a large church, solid-wall property or traditional stone building, maintaining a small amount of background heat can often be more effective than allowing the building to cool down and then trying to reheat it later.
A building doesn’t suddenly become cold in October.
It spends September quietly running out of stored heat from the summer.
How Woohoo Can Help
At Woohoo, we help building owners understand how their buildings actually behave, rather than relying on rules of thumb.
By looking at thermal mass, insulation, ventilation, moisture and heating controls, we can identify how a building stores heat, how quickly it loses it and whether the current heating strategy is working with the building rather than against it.
Sometimes the solution isn’t turning the heating on earlier or later.
It’s understanding how the building stores heat, manages moisture and stays comfortable throughout the year.
From October, households on standard variable tariffs will see another change to the energy price cap. The headline news is prices going up by 4% but what does that mean?
Electricity will cost approximately 26.32 p/kWh, up from 26.11 p/kWh, while gas will rise to 7.97 p/kWh from 7.33 p/kWh. Standing charges will also change, with electricity reducing from 57.19 p/day to 54.83 p/day and gas increasing from 29.04 p/day to 29.68 p/day.
This means that those primarily using electricity will be less affected by the new price cap than those using gas. This is in part due to the Government removing VAT from electricity. It also aligns with wider efforts to rebalance energy costs, with increasing discussion around moving some policy costs away from electricity in order to encourage electrification.
For many households, the immediate effect will simply be higher bills as autumn approaches as heating systems begin to switch back on.
Why Are Prices Rising?
Energy prices can often feel very disconnected from what is happening locally.
The UK now generates increasing amounts of renewable electricity, yet household bills remain heavily influenced by international gas markets. This is because natural gas still plays a major role in both heating homes and setting electricity prices during periods when renewable generation cannot meet demand.
This summer has provided a good example of that dependence and the following charts of the Octopus Tracker tariffs illustrated by Agilebuddy.uk provide quite a good illustration.
Gas prices over last winter were relatively stable apart from a brief period in late January likely reflecting a combination of colder weather, depleted supplies, lower wind and geopolitical uncertainty.
The big change came after the conflict in the Middle East began as this disrupted the supply chain significantly increasing prices and also after Europe had got to spring with gas reserves lower than normal. The next knock on effect has been the price in late summer that’s likely been driven by the heat waves. Late summer is typically a time when gas supplies are getting replenished in time for winter but they are more depleted than normal.
The heat waves have increased cooling demand that have increased electricity demand. The high pressure has meant less wind generation and due to the heat across Europe and several nuclear reactors across Europe have had output reduced or have been temporarily shut down because high river temperatures and low river flows limited cooling capacity.
This has meant gas has increasingly been used to generate electricity at a time when gas reserves are needing to be replenished ahead of winter.
This is all leading to predicted higher costs on the Wholesale gas markets.
Electricity whilst still heavily connected to the gas price due to the marginal pricing system the market currently uses is beginning to slowly disconnect itself from the volatile gas market and this can be seen from the Octopus Tracker Tariff. The days when renewable generation is high the price drops significantly and the days when the grid is using a reasonable amount of gas, the gas price sets the electricity price.
What can you do?
It’s possible to still get fixed rate tariffs ahead of the price cap but the likelihood is if your building is heated by oil or gas then it is probably going to be a more expensive winter. Unfortunately, heating oil is not protected by the price cap so prices of this will likely be even higher.
The primary focus should be beginning to look into ways to source your buildings energy from electricity rather than fossil fuels. This may be fitting solar panels, getting batteries, shifting heating/cooling to a heat pump etc all of which reduces the amount of fossil fuel we need to buy that gets shipped from other parts of the world. There are grants in place to help with this and have been for possibly 15 years trying to encourage people to make this switch.
A good first step is likely to be ensuring you have a working smart meter as this enables access to the best tariffs as then the energy company is able to see at what point in the day you are using electricity so can offer you beneficial tariffs if you can shift your electricity consumption.
The bigger picture: how do we reduce the electricity price?
The overall electricity price is generally dictated by the gas price and the daily electricity price spike between 4-8pm. This happens when the sun goes down and people go home and turn on various appliances leading to a daily wholesale price spike. The generalised UK approach to this is increase renewable generation while shifting demand away from the 4-8pm peak and deploying more battery storage.
The daily price spikes can be seen in the Octopus Agile tariff below illustrated by Octoprice.app.
Interestingly, parts of Australia are now demonstrating how large amounts of solar and battery storage can significantly reduce evening wholesale price spikes and lower overall electricity costs. Whilst they haven’t removed this evening peak entirely they are getting closer to doing so with large amounts of battery storage.
The common approach for an increasing number of UK households have been to fit solar panels and batteries to disconnect themselves from the grid price and generate their own electricity. Energy companies have also been offering increasingly innovative electricity tariffs to incentivise people to shift their energy usage outside of this 4-8pm window.
It is going to be an expensive winter from the predicted natural gas price but there are definitely opportunities if you are able to electrify and shift your consumption to different times of the day.
How Woohoo Can Help
At Woohoo, we help people understand where their energy costs are really coming from and what can be done about them. Rising prices often lead straight to thoughts of major upgrades, but the biggest opportunities are not always the most obvious ones.
We start by understanding how a building uses energy today. That might mean reviewing utility data, assessing heating systems, identifying wasted energy or exploring whether technologies such as heat pumps, solar PV, battery storage or smart tariffs could reduce exposure to future price rises. Understanding current performance is often the first step towards making informed investment decisions.
The goal is not simply to reduce the next bill. It’s to create a longer-term strategy that makes buildings more comfortable, more efficient and less dependent on volatile fossil fuel markets.
For centuries, buildings have been remarkably simple.
Heat escaped through draughts, moisture dried naturally through ventilation, and indoor temperatures closely followed the weather outside. Buildings were often uncomfortable and inefficient, but they were also surprisingly tolerant of things not being perfect.
Over the last few decades, that has changed dramatically.
To reduce carbon emissions and energy consumption, modern buildings have become increasingly airtight and insulated. These improvements have delivered enormous benefits, but they have also shifted much of the responsibility for comfort and efficiency away from the building fabric and onto the systems serving it.
The challenge today is no longer simply building a better building.
It is ensuring that increasingly complex systems are properly designed, commissioned, reliable and simple for occupants to operate.
The question has become:
What systems does a building rely on?
What happens when they aren’t working as intended?
Heating Systems: Small Changes, Big Impacts
In older buildings, heating systems are often pretty crude.
A boiler supplied water to radiators at high temperatures and occupants adjusted comfort by opening windows, turning thermostats up and down or simply just off and on.
Modern heating systems are far more sophisticated.
Heat pumps, weather compensation controls, zoning systems, underfloor heating and smart controls can significantly reduce energy consumption while maintaining comfort. However, these systems only achieve their promised performance when configured correctly.
A heat pump operating at unnecessarily high temperatures can dramatically increase electricity use. Poorly configured controls can lead to overheating, excessive cycling or rooms failing to reach their target temperatures.
Increasingly, the issue is not that a building lacks heating capacity. It is that the system requires careful setup and optimisation to ensure the heat efficiently gets in a building and then is effectively distributed around it.
Cooling Systems: A Growing Necessity
Historically, many UK buildings required little or no cooling.
The climate was generally mild enough that opening windows during warm weather was sufficient.
As summers become warmer and periods of extreme heat become more frequent, cooling is becoming increasingly important. Building fabric issues that just mean a slightly bigger bill in the winter months can mean huge discomfort for occupants in the summer months.
Most buildings in England are dependent of overnight window or door opening to cool them down with cooler overnight air. As the days and nights have got warmer buildings have become hugely dependent on this overnight ventilation that is dependent on occupant action or simply may not be possible or practical.
Cooling can come in many forms:
Mechanical night purge ventilation systems
External shading controls
Air conditioning
Reversible Air-to-Water heat pumps
The challenge is that cooling systems often interact closely with the building itself.
A poorly shaded building may require far larger cooling systems than originally expected. Similarly, cooling systems may perform poorly if controls are incorrect or ventilation strategies are not coordinated.
Good cooling design is increasingly becoming a necessity rather than a luxury.
Ventilation and Indoor Air Quality
Perhaps the clearest example of growing system dependence is ventilation.
Traditional buildings leaked air continuously through gaps and cracks. Even traditional buildings these days often have had a lots of their draughts minimised over time.
Modern buildings are intentionally sealed to minimise heat loss. While this dramatically improves energy efficiency, it also means fresh air can no longer be left to chance.
Instead, buildings increasingly rely on systems:
Manual window and door opening
Mechanical extract ventilation
Positive input ventilation systems
Mechanical Ventilation with Heat Recovery (MVHR)
Air quality controlled ventilation (in high end environments)
When these systems are working correctly, indoor environments can be healthier, quieter and more energy efficient than ever before.
When they are not, occupants may experience:
Poor air quality
Excess humidity
Condensation
Mould growth
Overheating
Increased energy use
Ventilation systems often require regular maintenance, filter replacement and commissioning checks to continue performing as intended.
Domestic Hot Water Systems
Hot water is another area where modern buildings have become increasingly reliant on controls.
To improve efficiency, many systems now include:
Heat pumps
Solar thermal systems
Thermal stores
Smart immersion controls
Time scheduling
Legionella protection cycles
These systems can reduce energy use significantly but often require careful setup.
Poorly configured timers, excessive water temperatures or incorrect control settings can increase running costs without improving comfort. They do represent an opportunity as hot water cylinders can often be reheated at off-peak times, making use of reduced energy prices.
Renewable Energy Systems
Many buildings now generate a proportion of their own energy or make use of the outside environment. This flips the conventional model on its head as there is much more energy outside than there is inside and how can that be harnessed to make huge gains in building performance.
Examples include:
Heat Pumps
Solar PV
Battery storage
Smart EV charging
Export controls
Energy management systems
These technologies can deliver substantial savings, but only when they operate together effectively.
It is increasingly common to find buildings where expensive renewable technologies have been installed but are not performing as expected because settings have never been reviewed following installation.
Sensors, Controls and Automation
Modern buildings are increasingly becoming data-driven.
Temperature sensors, occupancy sensors, CO₂ monitors and smart controls continuously influence how systems operate.
In many cases, the controls have become just as important as the equipment itself.
The reality is that a perfectly sized heating or ventilation system can still perform poorly if sensors are located incorrectly or control strategies are misunderstood.
Often, energy waste occurs because systems are simply fighting each other:
Heating and cooling operating simultaneously
Ventilation rates set too high
Hot water unnecessarily maintained at peak temperatures or not heated at off peak times
Controls overridden and never reset
Commissioning: The Often Forgotten Stage
The unfortunate reality is that many systems are installed correctly but never fully commissioned. This agonisingly may mean they never reach their full potential but it may only be one simple setting change away.
Commissioning is the process of ensuring every component operates as intended and that the whole building works together as a single system.
Without commissioning:
Energy use can be significantly higher than expected.
Comfort problems can persist.
Equipment lifespan may be reduced.
Occupants often lose confidence in the building.
A building’s long-term performance frequently depends more on commissioning and ongoing optimisation than on the equipment itself.
A New Era of Building Performance
The buildings of the future are unlikely to become simpler.
In fact, they will probably become even more dependent on carefully integrated systems. However, there is progress being made to make controlling these systems simpler to the occupant or setup so they just work and never have to be changed.
Heat pumps, ventilation systems, renewable energy technologies, smart controls and cooling systems all have important roles to play in helping buildings respond to rising energy costs and a changing climate.
The opportunity is enormous.
When these systems are operating properly, buildings can be healthier, more comfortable and far cheaper to run than previous generations ever achieved.
The challenge is making sure those systems are actually doing what they were designed to do.
How Woohoo Can Help
We help clients understand how their buildings are really performing.
Modern buildings rely heavily on systems such as heat pumps, ventilation, cooling and controls to deliver comfort, good air quality and low running costs. Even well-designed buildings can underperform if these systems are not properly commissioned, configured or maintained.
We work with clients to assess:
Heating and cooling performance
Ventilation and indoor air quality
Energy consumption and running costs
Overheating and occupant comfort
Renewable energy systems
By combining building physics with real-world operational data, we help identify where energy is being wasted, where comfort issues are occurring and what practical improvements will deliver the greatest benefit.
As buildings become smarter and more dependent on technology, understanding how those systems work together is becoming just as important as the building itself.
The goal is simple: comfortable, healthy buildings that perform as intended while keeping energy use and running costs under control.
For years, installing solar PV has required a full electrical installation, scaffolding, roof-mounting systems, specialist electrical work, and a large investment.
A new type of system known as plug-in solar or balcony solar aims to simplify that process. From 27 August 2026, small plug-in solar systems of up to 800 W will be permitted in the UK, allowing homeowners to install a system themselves without the complexity associated with traditional rooftop solar installations.
But what exactly is plug-in solar, how does it work and is it likely to change the way we generate electricity at home?
What Is Plug-In Solar?
At its simplest, plug-in solar is a small solar PV system designed to connect directly into a standard electrical socket.
Rather than being permanently wired into your consumer unit like a traditional solar installation, the system generates electricity during the day and feeds that power directly into your home’s electrical circuits through a dedicated plug connection.
If your home is using electricity at the same time, appliances will simply use the solar energy first before importing power from the grid.
Example of two 400W panels plugged into a microinverter similar to a plug in array
What Components Does A Plug-In Solar System Need?
Although the installation is much simpler than a traditional rooftop system, the key components remain broadly the same. It requires a little more DIY than just plugging in but is similar to the time taken to put together a piece of flat pack furniture. The components are the following.
Solar panels to generate electricity from sunlight. Usually 2 panels make 800W and they are quite sizeable.
A microinverter that converts DC electricity from the panels into AC electricity suitable for the home. Small, simple to plug and often has an app to show you how much you are generating.
Mounting equipment for a roof, wall, garden or balcony location.
A suitable plug-and-play connection system to connect the panels to the microinverter
Optional battery storage to store excess generation for later use. This isn’t legalised yet but is expected in 2027.
Why Is It Being Considered?
Traditional solar installations can require significant upfront costs and often aren’t suitable for every property.
Plug-in solar could potentially provide:
Lower installation costs.
Reduced installation complexity.
Opportunities for flats and apartments.
Easier relocation if occupants move home.
A simple first step into renewable energy generation.
For many people it could become the equivalent of a “starter solar system”. It is expected you will see these systems suddenly become widely available in the £250-£500 price bracket.
How Much Will It Generate?
So 800Wp is not a big solar array but at £250-£500 it suddenly is much more affordable. In August 2026 according to MCS the average solar array install is £8400 and 5250Wp (notably this often includes batteries).
We’ve been testing this size of system during the summer and on a really clear July day the 800Wp rated panels generate around 600W of electrical power at peak sun (and when the panels are cool). To provide some context, a big TV may use 200W, a kettle 3000W, a hair dryer 1500W, a vacuum 1000W, etc. It’s definitely some electricity, but it’s not vast quantities at this small scale. It will reduce bills but not cover all the consumption.
On a clear day in summer it generated approximately 4.5kwh of electricity and in the month of July it generated 90kwh when sun power is highest. This will drop significantly in the winter months and in some ways the timing of the legislation is unfortunate as the generation will be reducing heading into winter due to the shortening of days.
Example of our 800W test array from July 2026
Is It Cost-Effective?
In short, yes, but it has its limitations. The payback for it depends on:
– How much direct sun hits the panels and in turn how much electricity is generated
– How much of that electricity the building uses directly as without batteries or an export tariff the excess will be going back to the grid.
– What electricity tariff you are on. A tariff that is expensive during the day (e.g. and EV tariff) will save more money than one that isn’t.
A payback for a large rooftop solar array is commonly around 10 years. Plug-in solar, if all the electricity is consumed by the building, could be less than this, but with a high amount of shading or a lot of the electricity goes back to the grid free of charge, it will be more than this. It is expected to pay back within the lifetime of the system.
It is expected that plug-in batteries will arrive shortly and these will greatly improve the cost-effectiveness.
The Hidden Benefits
Often what consumers are really purchasing with solar panel arrays is energy security and slowly disconnecting themselves from volatile fossil fuel markets. This is difficult to put a price on but for many, this security is really high value. Large rooftop solar arrays are likely better financial investments, but there are benefits to these smaller systems.
– The upfront cost is significantly reduced making renewable energy far more accessible.
– Showing the power available in sunlight should help drive electrification, hopefully leading to lower costs for all.
– These more temporary solar installations can often be easily re-angled for summer and winter sun angles making better use of the sun at different times of year.
– They can often be angled to generate electricity when home consumption or the grid price is highest, reducing bills even further.
– Commonly, they are much more accessible and so can be cleaned more regularly and generate more electricity.
– They can be easily moved if changing property or a better location in a garden is found
– There may become a good second-hand market as systems theoretically can be unplugged and sold on and with lifespans of 25 years could make very good investments
The Bigger Picture
There are lots of great pieces of content available about peoples personal experiences when testing these microarrays and what the paybacks are. However, it gets really interesting when looking at the bigger picture.
Over time, Britain’s electricity grid has been shifting from large-scale power plants to huge numbers of renewable micro-generators. Each solar array is decreasing Britain’s reliance on fossil fuels and improving its resilience to fossil fuel shocks. So a generation of 90kwh in July may not sound like much, but it’s 90kwh of fossil fuel that doesn’t need to be shipped from somewhere else in the world. When you account for power station and transport efficiencies, this may be as much as 180kwh less natural gas that needs to be shipped from somewhere else in the world.
It’s these knock-on effects that are fascinating, as it should slowly reduce the relative grid electricity price for everyone as each customer will have a smaller dependency on grid energy.
At Woohoo, we think the real power will be in education and showing people the power and potential of electrification. Often when people get solar panel arrays they then quickly transition to electrical technologies once they’ve seen the potential and the cost savings of renewable technologies. Heat pumps, batteries, EVs, large solar arrays, etc are big investments, but a small microsolar array can suddenly show the potential in electrification with a much smaller cost barrier.
The Likely Future: Plug-In Batteries
Plug-in solar is a great step forward. It still has some issues to work through but with this legislation solar will become very common, costs will continue to drop and it will become ever simpler to install. Importantly, it will become affordable for significantly more people.
Plug-in solar has been aimed at customers with flats and whilst it should pay back for these customers, multiple factors such as shading, sun angles, time of generation etc will likely make it much less cost-effective.
In the very near future, it is expected that plug-in batteries will come into legislation and these will be very exciting and much more cost-effective for flats. These will be much simpler to plug in and will start saving immediately across all times of year.
The exciting part is the issue with our national energy systems have is less one of generation but more one of storage. Renewable electricity is very cheap to make but we don’t have enough storage currently and so having to frequently turn down generation.
If every home had a small battery, then suddenly we can maximise the already existing grid infrastructure and heavily reduce grid electricity prices. This won’t happen immediately but at scale will have a huge impact. There are rumours that there will be large-scale schemes put in place where houses are given plug-in batteries as the reduction to the national electricity price far outweighs the price of the battery and can hugely reduce the cost of living for those most in need.
The next 12 months could be really exciting…
How Woohoo Can Help
At Woohoo, we’re constantly assessing emerging technologies that may help buildings reduce energy consumption and carbon emissions.
As plug-in solar develops, understanding the expected generation, potential savings and integration with battery storage will be key to delivering the best results.
The question isn’t just whether plug-in solar works – it’s where it makes sense, who it benefits most and how it can be deployed safely and effectively.
Most people think of heat pumps as a low-carbon replacement for a boiler. They provide heating in winter, hot water year-round, and can help reduce energy bills.
What many people don’t realise is that a growing number of air-to-water heat pumps can also operate in reverse and provide cooling during the summer.
This summer, we’re increasingly seeing people switch their heat pumps to cooling mode to help keep them more comfortable. Over the summer, we’ve switched many systems from heating mode into cooling mode and in the right scenario the results can be surprisingly effective.
However, cooling a building with a heat pump isn’t as simple as turning the temperature down. The performance depends heavily on the building itself, the type of emitters installed and the risk of condensation.
Air Conditioning is a relatively mature technology, but is there a big cooling opportunity with the Air-to-Water heat pumps increasingly getting installed in homes?
How does a heat pump cool a building?
In cooling mode, the heat pump simply reverses the process used for heating. Instead of extracting heat from the outside air and bringing it indoors, it removes heat from inside the building and rejects it outside.
The challenge then becomes how to actually remove the heat from the rooms and then put it outside.
Underfloor Heating and Cooling
Underfloor heating often works surprisingly well as a cooling system and as often it’s getting installed to get a high-efficiency heating installation it also lends itself well to doing the same when cooling.
Rather than creating cold draughts, the floor becomes slightly cooler than the room and gently absorbs heat from the space above. This creates a very comfortable environment because the cooling is spread across a large area.
A typical cooling floor might operate at around 18-22°C rather than the much colder temperatures found in air conditioning systems.
The advantages include:
Very quiet operation
No visible equipment
Uniform temperatures throughout the room
Good comfort levels
Although it provides cooling across a really large area, the limitation is cooling power before condensation starts to accumulate across the floor.
A floor can only absorb so much heat before its temperature approaches the room temperature. This means underfloor cooling works best in well-insulated buildings with modest solar gains rather than highly glazed properties with large overheating issues.
Can Radiators Be Used for Cooling?
In theory, yes. A standard radiator supplied with cool water will absorb heat from the room.
The problem is that radiators usually have relatively small surface areas and have been designed for heating so the hot water rises in them. While they work well with 35°C+ water during heating mode, they become far less effective when supplied with 18-20°C cooling water and really prone to condensation.
The cooling output is often only a fraction of the heating output.
This means conventional radiators can provide some background cooling but are rarely capable of removing enough heat to control temperatures during a severe heatwave. Vertical radiators can work better as can access the warmer air higher in the room but still generally struggle to perform as well as underfloor cooling.
Fan-Assisted Radiators
Fan-assisted radiators (sometimes called low temperature radiators or fan convectors) bridge the gap between standard radiators and full air conditioning.
A small fan moves room air across the heat exchanger, dramatically increasing the amount of heat that can be absorbed.
Compared with standard radiators they offer:
Higher cooling output
Faster response times
Better room temperature control
Create more noise
Smaller physical sizes
For existing heat pump systems, fan-assisted emitters can often provide a significant improvement in summer comfort without requiring a completely separate cooling system. The issue is usually that in Britain these have been designed for heating and so don’t have a mechanism to handle condensation accumulating if the temperature is too low.
The Condensation Challenge
The biggest limitation with heat pump cooling is normally not cooling power. It’s condensation.
Everyone has seen a cold drink form water droplets on the outside of the glass. Exactly the same thing can happen on cooling pipes, radiators and floors.
When a surface becomes colder than the dew point temperature of the surrounding air, moisture condenses onto that surface.
This can lead to:
Wet floors
Condensation on pipework
Damage to finishes
Mould growth
Potential long-term building issues
To avoid this, cooling systems need to carefully control water temperatures. In current British heatwaves dew point can be around 16-18°C depending on the weather.
This is why most air-to-water heat pumps operate with relatively modest cooling temperatures compared with traditional air conditioning systems.
Why Every Building Behaves Differently
“Will switching my heat pump into cooling mode make my house cool?”
Unfortunately, there is no simple answer.
The effectiveness depends on three key factors:
Solar Gains
Large areas of unshaded south or west-facing glazing can introduce significant amounts of heat into a building.
In many homes, solar gain remains the main cause of overheating. If sunlight is continuously adding heat faster than the cooling system can remove it, temperatures will continue to rise.
Internal Gains
People, appliances, lighting, cooking and hot water systems all generate heat.
Every unit of electricity used within a building eventually becomes heat somewhere indoors.
Building Fabric
Highly insulated buildings often perform surprisingly well with heat pump cooling because their cooling demand is relatively modest and temperatures change slowly.
In contrast, poorly insulated buildings let a lot of heat in which raises the amount of cooling required.
The building itself ultimately determines whether a heat pump cooling system feels transformational or merely a little helpful.
Could Fan Coil Units Be the Future?
As cooling demand increases, many designers are beginning to view heating and cooling as part of the same system.
One possible future as an alternative to air conditioning could be a heat pump connected to:
Underfloor heating for winter comfort
Domestic hot water production
A cooling circuit with fan coil units for the summer
Fan coil units look similar to slim radiators but contain larger heat exchangers and fans that can deliver significantly more cooling capacity. The key difference is when they generate condensation it is collected and piped outside so the temperature can be run much lower.
This approach allows buildings to use one piece of equipment throughout the year, providing heating in winter and effective cooling during increasingly frequent summer heatwaves.
For many homes, especially those with large areas of glazing or home office spaces, this may become a more practical solution than installing a completely separate air conditioning system to help with the summer months.
How Woohoo Can Help
At Woohoo, we regularly look into overheating risk, cooling demand and heat pump performance as part of our building performance work.
Every building is different. The amount of cooling available from a heat pump depends on the building’s insulation level, glazing, ventilation strategy and internal heat gains.
By understanding where the heat is coming from and how quickly it can be removed, we can help identify what systems likely to provide the best result.
The goal is simple: how do we make great sustainable spaces that are comfortable in the future.
During a heatwave, many people assume that hot air outside is the main reason their building becomes uncomfortable. In reality, most overheating problems are caused by a combination of heat gains from several different sources, all adding heat faster than the building can remove it.
The challenge is that buildings behave a bit like a thermal battery. Throughout the day they absorb heat from the sun, occupants, lighting and appliances. If this heat cannot escape overnight, the building starts the next day already warm and temperatures continue to climb.
Understanding overheating therefore comes down to two simple questions:
1. Where does the heat come from?
2. Why can’t it get out?
Part 1: Heating – Where Does the Heat Come From?
Solar Gain: The Biggest Contributor (50-70%)
In most homes, solar gain through glazing is by far the largest source of overheating during a heatwave. Sunlight enters through windows and is absorbed by walls, floors and furniture. These surfaces then re-radiate heat into the room, creating the familiar greenhouse effect.
A typical south or west-facing window can admit hundreds of watts of heat during sunny periods. In many modern well-insulated buildings, solar gain can account for well over half of the total heat entering the building on a hot day. This is why external shading often provides more overheating benefit than additional insulation.
Building Fabric (10-20%)
Roofs, walls and windows also absorb heat directly from the outside environment. Dark roofs can reach temperatures of 60-80°C on sunny days, transferring some of this heat into the occupied spaces below. Poorly insulated lofts and roof spaces are particularly prone to this effect.
However, contrary to popular belief, heat transfer through walls is often a smaller contributor than direct sunlight through glazing. Often it’s uninsulated roofs that provide large heat gains in the building fabric
Occupants (5-10%)
People are effectively small heaters.
An adult sitting quietly typically emits around 70-100 watts of heat. A family occupying a house may contribute the equivalent of several hundred watts continuously, particularly during evenings when windows are often closed for security or noise reasons.
Appliances and Lighting (10-20%)
Every unit of electricity used inside a building eventually becomes heat. Computers, televisions, cooking appliances, hot water systems and lighting all contribute. A gaming PC can release several hundred watts. An oven can release several kilowatts while cooking. Even efficient LED lighting ultimately converts its energy into heat within the room.
These gains are often overlooked because they are less obvious than sunshine through a window.
Ventilation and Hot Outdoor Air (5-15%)
Opening windows during the hottest part of the day can make overheating worse.
If outside air is warmer than the internal air temperature, ventilation becomes a source of heat gain rather than cooling. Buildings therefore need carefully timed ventilation rather than simply opening every window whenever it feels warm even if the strong breeze makes things feel much more comfortable.
Part 2: Cooling – How Does the Heat Escape?
Getting heat out of a building relies on surprisingly few mechanisms.
Ventilation
The most effective cooling method available to most buildings is moving cooler outside air through the building. When night-time temperatures fall, opening windows or using mechanical ventilation allows stored heat to be carried away by the cooler air.
The greater the airflow, the faster cooling occurs. It’s this overnight airflow that has the greater impact in cooling buildings. Ideally looking to be capable of 5+ air changes per hour which is a large continuous draught.
Unfortunately, during still nights there may be very little natural air movement, so simply opening windows does not always provide the cooling people expect as the temperature or humidity difference alone is not enough for the air to flow at a significant speed.
Night Purge Cooling
The goal of night ventilation is not primarily to cool the air.
Instead, it cools the building fabric itself. Walls, floors and ceilings often store far more heat than the air in the room. If these surfaces can be cooled overnight, they effectively reset the building ready for the next day.
This explains why a house can still feel hot at midnight even after outside temperatures have fallen. The goal of night purge cooling is to flush the building with as much cooler air as possible. Often this requires fans near windows to help draw the air through the building.
Radiation to the Night Sky
Buildings also lose heat through radiation. Roofs, walls and external surfaces continuously emit heat to their surroundings. On clear nights they can become surprisingly effective at shedding heat directly to the sky.
While invisible to occupants, this process contributes to overnight cooling and is particularly important for lightweight roofs.
Thermal Mass
Thermal mass often receives mixed publicity because it can both help and hinder overheating.
Heavy materials such as concrete, stone and brick absorb heat during the day and slow temperature rises. However, if the building cannot cool at night, that stored heat remains in the structure and may contribute to overheating for several days.
Thermal mass can therefore be really helpful as it can slow the building heating up but needs a lot of cooling air flow to draw the heat out of the building fabric.
Active Cooling
When natural ventilation and shading are insufficient, active cooling may be required. With more frequent heat waves we are getting more nights where the outdoor temperature doesn’t drop below 20 degrees C and thus air needs to be moved much faster through the building overnight to cool it.
Air conditioning removes heat directly from the building and rejects it outdoors. While highly effective, it should generally be considered after first reducing solar gains and improving ventilation opportunities to reduce the amount of cooling required.
A number of people with heat pumps and underfloor heating are switching their heat pumps into cooling mode which can give a very significant cooling effect by removing heat from the floor slab. Whilst effective, care should be taken with this as cold surfaces can create condensation and lead to building issues.
A surprising amount of overheating can often be solved without installing significant cooling equipment.
How Woohoo Can Help
At Woohoo, we help clients understand exactly why their building overheats as part of their wider energy and sustainability strategies. Every building behaves differently, and measures that work well in one property can sometimes have little effect in another.
By assessing heat gains, ventilation pathways and building fabric performance, we can identify where the heat is coming from, where it is getting trapped, and which improvements will provide the greatest benefit.
The goal is simple: how can we make buildings more comfortable during increasingly frequent heatwaves while avoiding unnecessary energy use and cost.
Simon Lock, our Sustainability Director, recently completed Carbon Literacy training with Futureproof Cumbria. Here are some of his thoughts on making cleaner, cheaper energy choices easier to understand.
Did you know that when it’s windy and sunny, electricity can be both cheaper and lower carbon?
It’s a simple idea, but it rarely feels simple in practice.
For owners of older buildings, heritage assets and public estates, energy decisions are rarely straightforward. These buildings often come with higher running costs, fabric constraints, planning considerations and long-term responsibilities. Not every improvement can be made quickly, and not every building can be treated in the same way.
But some decisions can still be simpler than we make them.
What if everyday weather forecasts also told us when energy was cheapest and cleanest? Suddenly, small choices such as doing the laundry, charging an EV, running appliances or planning higher-energy tasks can become useful financial and climate actions.
The Carbon Literacy Project
As Sustainability Director at Woohoo, I spend a lot of my time helping reduce emissions across the built environment, particularly where buildings are older, listed, sensitive or difficult to change.
As part of my CPD last year, I undertook Carbon Literacy training with Futureproof Cumbria. While I already had a good knowledge of emissions, there are always opportunities to improve, question assumptions and look at where small actions can lead to wider change.
As part of the certification process with The Carbon Literacy Project, you make pledges on a personal and community level to find ways to collectively reduce emissions.
Like many people working in this space, I have already made significant personal changes, including switching away from fossil fuels and continuing to lower my own emissions where I can.
So the question became: what next?
From personal action to wider impact
One takeaway stood out: the importance of sharing knowledge with as many people as possible.
Not in theory, but in practice.
At the moment, the UK is still turning off large amounts of renewable energy, during an energy crisis.
When wind generation is high, turbines can be switched off because the grid cannot absorb the excess electricity. At the same time, we may end up using more expensive gas-generated electricity later, when demand rises and renewable generation is lower.
In 2026 so far, we have collectively spent over £800m turning off wind turbines, according to wastedwind.energy.
This is a huge missed opportunity. Not just for the energy system, but for households, businesses, building owners and local authorities who are all trying to manage bills and reduce emissions.
In many cases, the action itself is not complicated. It could be as simple as shifting daily tasks away from the late afternoon and early evening peak, or planning larger weekly tasks for times when renewable energy is more plentiful.
For heritage building owners, this does not replace the need for proper fabric-first advice, sensitive retrofit or long-term decarbonisation planning. But it can sit alongside those measures.
It is a low-disruption way to understand energy better, use it more intelligently and make existing buildings work harder before larger interventions are made.
The data already exists. Forecasts for wind and solar generation are produced continuously by the Met Office and the National Energy System Operator. But they are not always presented in a way that helps people act.
If you want to see this in practice, this website gives a useful view of forecasted emissions and prices: Click here
So why not make this forecast highly visible, as part of everyday life?
Making energy patterns visible
Imagine this as part of a standard weather forecast:
“High winds overnight — a good time to charge your EV.”
“Strong sunshine today — useful time to run appliances.”
“Still and overcast — energy likely to be more expensive and carbon intensive.”
Small signals. Scaled across millions of people.
For those on time-of-use tariffs, this kind of visibility could unlock real savings. In some cases, even allow people to earn money by using electricity when supply is high.
For everyone else, it builds awareness. And awareness drives change.
Only around 10% of buildings are on time-of-use tariffs and the vast majority of people could save money on these tariffs if they can make small adjustments to their usage patterns. If people moved to time-of-use tariffs they would respond to price cues that would be chasing renewable energy and get financially rewarded for doing so.
It will not solve every challenge. Heritage buildings still need the right advice, the right interventions and a proper understanding of their fabric, use and significance.
But better energy visibility can help people make better choices now, while those longer-term plans are developed.
Beyond cost: unlocking system-wide benefits
The impact goes further than individual bills. Better alignment between demand and renewable supply could:
Reduce wasted clean energy
Lower system costs
Encourage greater investment in renewables
Support grid stability
Help organisations reduce operational emissions
Support progress towards Net Zero
Importantly, it also makes low-carbon living more accessible.
Not something reserved for specialists. Not something only available through major capital projects. But something embedded into everyday decision-making.
For heritage and older buildings, that point is important. Decarbonisation is not always about doing the biggest thing first. Sometimes it starts with understanding the building, understanding the energy system, and making better choices with the information already available.
From insight to action
The Carbon Literacy Project has highlighted this campaign in their latest blog to try to help generate a ripple effect. Turning individual understanding into simple collective and effective action.
For me, that meant taking a simple idea and pushing it further: advocating for clearer, more accessible energy information and exploring how communication, not just technology, can unlock change.
Because the transition to a low-carbon future is not only about infrastructure.
It is about behaviour. It is about visibility. And ultimately, it is about people.
A simple takeaway
If it is sunny and windy, electricity is often cheaper and greener.
In the first two parts of the Hot Topic series, we explored running costs and energy consumption for common UK heating systems. This final section looks at the greenhouse gas emissions involved, using the same 100m² example home.
Emissions are shown as CO2E using the government’s latest conversion factors, which take into account all major greenhouse gases. Electricity figures reflect the current national grid mix, which still includes a large share of gas generation.
Hydrogen Boiler
Pros: No emissions from your building, potential for the future Cons: Currently costly to run and wastes energy in production
Hydrogen itself burns cleanly but producing it requires a huge amount of electricity. Green hydrogen, made entirely from renewables, has very low emissions, while hydrogen created using grid electricity has very high emissions. Its impact depends entirely on how it is produced.
Oil Boiler
Pros: A practical and widely used choice for properties that aren’t connected to the gas grid.
Cons: Produces some of the highest emissions of any commonly used heating fuel due to the nature of kerosene.
Kerosene is a fossil fuel and has the highest emissions of the fuels compared in this series.
Liquid Petroleum Gas (LPG) Boiler
Pros: A workable heating solution for off-grid homes where other fuels aren’t suitable.
Cons: LPG remains an expensive and carbon-intensive fuel despite its convenience.
LPG is another fossil fuel option, and using it for heating has a large amount of emissions associated with it.
Gas Boiler
Pros: A reliable, accessible and generally affordable heating method with lower emissions than other fossil fuel options.
Cons: Still dependent on a fossil fuel, so it contributes directly to carbon emissions.
Gas boilers are common in part because gas produces fewer emissions than oil or LPG leading to improved air quality.
Electric Storage Heaters
Pros: Straightforward to install and well-suited to smaller, well-insulated spaces where heat demand is modest.
Cons: Running costs climb quickly in larger or draughty homes, especially when powered by grid electricity that still includes a significant gas contribution.
Electric heating only becomes low-emission when powered by clean electricity. As much of the UK grid still relies on gas, emissions for storage heaters currently sit close to gas heating. A renewable tariff helps push the grid in the right direction towards net zero.
Electric Infrared Heaters
Pros: Inexpensive to install and effective for heating specific areas rather than whole rooms, helping keep energy use down when managed properly.
Cons: Poor use can lead to cold spots, condensation and damp issues, particularly in buildings heated intermittently.
Infrared heaters operate at almost 100% efficiency and use less energy because they are easy to target. Problems arise when buildings are under-heated, leading to cold spots, condensation and mould, especially when users switch them on only when inside the building.
Air Source Heat Pumps
Pros: Capable of delivering lower running costs than gas when well-installed, with government grants available to support the upfront investment.
Cons: Installation is costly and performance can dip in very cold conditions, so not every home will achieve the same level of efficiency.
Heat pumps create far more heat than the electricity they consume, so their emissions are much lower than boilers or resistance heating. This efficiency is a major reason behind the government’s net-zero strategy.
Ground Source Heat Pumps
Pros: Extremely efficient with low energy consumption thanks to the stable temperatures beneath the ground.
Cons: Installation can be expensive and complex, often requiring extensive groundwork that limits where they can be used.
Ground source systems use even less electricity than air source models, resulting in lower emissions. However, cost and installation requirements limit where they are suitable.
Log Burner
Pros: Can be relatively inexpensive to fuel and works well in off-grid settings.
Cons: Delivers heat to a limited area and is less efficient than modern whole-house heating systems.
In theory, emissions can be lower than heat pumps at present because sustainably sourced wood can have its carbon reabsorbed over time. However, log burners are inefficient, heat only small spaces and rely on forestry that cannot scale nationwide.
Biomass Boiler
Pros: A renewable heating option with running costs that compare favourably to fossil fuel systems.
Cons: Requires dedicated storage space and regular fuel deliveries and isn’t suitable everywhere due to fuel supply and sustainability considerations.
Biomass boilers currently have the lowest operational emissions because their carbon cycle is relatively short. They still produce other greenhouse gases, require significant fuel storage and depend on sustainable forestry that cannot meet UK-wide demand. They are effective where waste wood is plentiful, but not a scalable national solution.
Summary
The direction of government policy becomes clear when you consider emissions. Electricity offers the best pathway to net zero because it can be fully decarbonised. Heat pumps reduce overall energy demand and generate far fewer emissions, making them the strongest large-scale option available today. Other technologies will still have their place, but heat pumps remain the most practical route for households aiming to cut their carbon footprint.
As the UK’s storm season sets in, homes and commercial buildings across the country are tested, but older and heritage buildings often feel it more. From draughty windows to leaking roofs, traditional materials and designs mean these properties can need extra care when the weather turns cold, wet, and windy.
This blog explores small but effective ways to protect your heritage building, save money, prevent damage, and stay comfortable through the winter.
1. Keep the rain out: gutters, downpipes and roofs
Blocked gutters and cracked downpipes can quickly lead to leaks and water damage, particularly during prolonged periods of rain. Regularly clearing debris and checking for blockages keeps water moving away from the walls and foundations rather than soaking into them. It’s also worth remembering that drier building fabrics are far cheaper to heat; it takes a surprising amount of energy to warm up moisture held within walls, floors and roofs, so keeping water out directly supports lower heating bills.
Likewise, inspecting the roof for loose slates or tiles can help prevent moisture finding its way inside and causing costly internal damage during storms.
2. Cut the draughts, not the character
Heritage homes often lose heat through ill-fitting doors and windows. Weatherstripping and discreet draught-proofing can make a noticeable difference without altering the building’s appearance. Reducing air leaks not only keeps interiors warmer but also helps lower energy bills during extended cold spells.
3. Prepare your heating system
Before the worst weather hits, bleeding radiators ensures they’re running efficiently and delivering consistent warmth. In older buildings where heat loss can be high, every bit of efficiency counts it’s a simple, quick job that can make your system more effective when you need it most.
4. Make use of windy weather
High winds aren’t all bad news they can mean lower-cost, low-emission electricity on dynamic tariffs. If your home uses modern energy solutions, such as smart meters or variable tariffs, keeping an eye on when wind energy peaks could save you money while reducing carbon impact.
5. Manage airflow and prevent unnecessary heat loss
Ventilation is vital for heritage buildings, but too much can make interiors uncomfortably cold. Adjusting or temporarily closing a proportion of vents in extreme weather can strike a balance between preventing damp and retaining warmth. Windbreaks, such as hedges or fencing, can also reduce direct wind exposure and the rate of heat loss from external walls.
Caring for a heritage property through winter doesn’t need to be complicated. Regular checks, simple maintenance, and a few smart adjustments can go a long way toward keeping your building warm, dry, and efficient, without compromising its character. If you’re unsure where to start, our expert team can help you assess your building’s condition and find the most effective, sympathetic improvements for your home.
If you own a heritage building or home, talk to us about improving its comfort and performance this winter. Get in touch with us today.
