Discover how commercial roof insulation, roof replacement and solar PV can improve energy performance, reduce energy demand and support a stronger EPC rating.
A commercial Energy Performance Certificate (EPC) measures the energy performance of a non-domestic building and gives it a rating from A to G, with A representing the most energy-efficient performance. For commercial property owners, landlords and businesses, improving the EPC rating can support lower energy demand, better building performance and stronger property marketability.
The roof can play an important role in that improvement. An inefficient commercial roof can contribute to heat loss, poor thermal performance and higher demand from heating and cooling systems. Replacing an outdated roof, improving insulation and addressing weaknesses in the building envelope can therefore contribute to better energy performance.
Solar photovoltaic (PV) systems approach the problem from another direction. Instead of reducing the building's energy requirement through the fabric of the property, solar generates electricity on site. The energy performance calculation for non-domestic buildings can take account of energy generated by technologies installed at the building, so renewable generation can contribute to the overall assessment.
Roofing and solar can therefore work together as part of a wider commercial energy-efficiency strategy. However, neither a new roof nor solar panels automatically guarantees a specific EPC rating. The final EPC depends on multiple characteristics of the building, including construction, roof and wall performance, heating, cooling, ventilation, hot water, lighting and other building services.
An EPC is an assessment of a building's energy efficiency. Commercial EPCs apply to non-domestic properties and use an A-to-G rating system. The certificate provides information about the building's energy performance and recommendations for potential improvements. GOV.UK states that an EPC is generally required when commercial premises are constructed, sold or rented out, subject to applicable exemptions. Commercial EPCs are valid for 10 years.
The assessment considers more than the roof. Factors can include:
That distinction matters when planning a commercial roof and solar project. A roof upgrade may improve the building fabric, while solar can contribute through renewable electricity generation. Combining both can address two different areas of the building's energy performance.
A commercial roof forms part of the building envelope. If the roof has inadequate insulation, damaged insulation or an inefficient construction, heat can move through the roof more readily. In a heated building during colder weather, this can increase heat loss. During warmer conditions, poor thermal performance can also make temperature control more difficult.
The EPC methodology considers the thermal performance of the roof as part of the building fabric. Government guidance specifically identifies roofs among the construction elements considered when assessing a non-domestic building.
A commercial roof upgrade can involve:
A roof replacement is therefore not only a waterproofing project. When designed correctly, it can become part of a broader building-energy improvement programme.
Insulation is one of the most direct links between roofing and thermal performance. The purpose of insulation is to reduce heat transfer through the building fabric. In a commercial property, the roof can represent a significant area of the external envelope, particularly in warehouses, industrial units and large single-storey buildings.
If the existing roof has poor insulation, improving the roof's thermal performance can reduce the amount of heat escaping through the roof during heating periods. That can reduce the theoretical energy demand associated with maintaining internal conditions.
For a business owner, this creates an important opportunity when a roof is already due for replacement. Instead of replacing the external covering while leaving outdated insulation underneath, the complete roof build-up can be assessed. ERS Energy Ltd states that its commercial roof replacement process includes an assessment of the existing roof, structure and insulation, followed by an insulation upgrade where required.
This approach can help ensure that the roof replacement addresses the condition of the building fabric rather than simply installing a new weatherproof surface.
Yes, a new commercial roof can contribute to an improved EPC rating when the replacement improves the thermal performance of the building. But it is important to understand the wording.
A new roof does not automatically mean a better EPC rating. If the new roof simply replaces a damaged covering with a similar thermal specification, the improvement in EPC performance may be limited. If the project includes an appropriate insulation upgrade and improves the thermal performance of the roof, the impact can be more significant.
The final EPC rating still depends on the whole building. For example, a warehouse may have a newly insulated roof but inefficient heating, poor lighting and other weak points. Those factors can continue to affect the overall EPC result.
The most effective approach is therefore to identify the building's existing weaknesses before selecting individual upgrades.
When a significant portion of a commercial roof is replaced, Building Regulations can be relevant, including requirements concerning thermal performance. A roof replacement can be an opportunity to improve energy performance while the roof is already being opened up. A business owner should not wait until after the roof has been replaced to consider insulation — the roof specification should be developed with thermal performance in mind before materials are ordered. The exact requirements depend on the building and scope, so businesses should obtain project-specific advice. ERS Energy Ltd handles Building Control notification and sign-off as part of its projects.
Solar PV works differently from insulation. Insulation reduces energy demand by improving the building fabric. Solar panels generate electricity. For a commercial building, electricity produced by solar can be used to meet some of the building's electrical demand. Depending on the building's operating profile, this can reduce reliance on electricity supplied from the grid.
Government EPC guidance states that the energy performance calculation for non-domestic buildings considers energy generated by technologies installed in the building. This is why solar can be relevant to an EPC improvement strategy.
A rooftop solar installation can potentially:
The effect on the EPC rating depends on the building and the calculation methodology used for the specific property. There is no universal number of EPC bands that solar panels will add. The effect depends on building size, current EPC rating, electricity demand, solar system capacity, roof area, orientation, shading and many other factors.
For this reason, businesses should avoid claims such as "installing solar will automatically move your EPC from D to B." The correct approach is to model the building and understand which improvements are likely to have the greatest effect.
Roofing and solar address different parts of the energy-performance problem. Roof insulation improves the building fabric. Solar generates electricity. When combined correctly, the two measures can create a more complete energy-efficiency strategy.
Consider a commercial warehouse with an ageing roof and a large electricity bill. Replacing the roof with an improved insulated system can reduce heat transfer through the roof. Installing solar on the new roof can then generate electricity for the business.
The property owner has addressed both:
This can be more effective than treating roofing and solar as completely separate projects. ERS Energy Ltd provides both commercial roofing and commercial solar services and specifically offers combined roofing and solar solutions. Its solar service includes assessing roof condition during the solar site visit and planning roofing and solar work together where the roof requires attention.
Installing solar panels on an ageing commercial roof without assessing the roof's remaining service life can create unnecessary problems. Solar panels are designed to remain in place for many years. If the roof underneath requires replacement soon after the solar installation, the panels and associated equipment may need to be removed or disturbed to allow roofing work to proceed, creating additional labour, disruption and potential cost.
A better approach is to assess:
If the roof needs replacement, the roofing and solar projects can be planned as one programme. ERS Energy Ltd states that it checks roof condition during solar site visits and can plan roofing and solar work together when the existing roof needs attention. This integrated approach is particularly useful for warehouses and industrial buildings with large roof areas.
Energy efficiency starts with the building fabric. If a building loses a significant amount of heat through poorly insulated roof areas, its heating system has to work harder. Improving insulation can reduce heat transfer.
A commercial roof assessment should establish what is already installed rather than assuming the roof has no insulation. A survey can identify insulation thickness and condition, moisture, thermal bridging, damaged areas, previous roof alterations, existing membranes and roof deck condition. Improving the roof changes one of the inputs that contributes to the building's energy performance.
Thermal bridging occurs where heat can travel through parts of the building envelope more readily than through surrounding insulated areas. Commercial roofs contain numerous details where thermal performance needs to be considered — roof edges, fixings, junctions, structural elements, rooflights, penetrations, plant supports and upstands.
A professional roof specification should consider the complete roof build-up rather than focusing only on the membrane or external sheet. A new waterproof layer does not necessarily solve thermal weaknesses — the insulation strategy, detailing and construction need to work together.
Not every section of a commercial roof will produce the same amount of solar electricity. Solar design can consider roof orientation, available roof area, roof pitch, shading, panel arrangement, building electricity demand, structural capacity, existing equipment and access routes.
A solar survey should therefore look at the roof as both a physical structure and an energy-generation asset. ERS Energy Ltd states that its commercial solar design process assesses roof orientation, shading and energy use before designing a system around the building — preventing businesses from selecting a system based solely on the maximum number of panels that can physically fit.
Solar is particularly relevant to businesses that use significant amounts of electricity during daylight hours — manufacturing facilities, warehouses, distribution centres, offices, retail premises, workshops and commercial units.
A business that consumes electricity during the day can use solar generation as it is produced. Battery storage can also be considered where the business needs to shift some of its solar-generated electricity to later periods. The right combination depends on the building's electricity profile rather than simply the size of the roof.
Rooflights can be useful because they allow natural daylight into large commercial spaces. However, their thermal performance and condition also need to be considered. Older rooflights can deteriorate, become damaged or perform poorly compared with modern materials.
A commercial roof assessment should therefore consider rooflights alongside the wider roof system, balancing natural daylight, thermal performance, weatherproofing, safety, maintenance and replacement requirements. Where rooflights are being replaced as part of a wider roof project, the specification should consider their impact on the building's overall energy performance.
Roof insulation alone does not determine the EPC rating. Heating is another major component. A commercial building with an inefficient heating system can continue to have poor energy performance even after a roof upgrade.
Government guidance states that commercial EPC assessments consider heating, cooling, ventilation, hot water and lighting alongside the building fabric. A roof and solar project can therefore be one part of a larger energy improvement programme. The building owner may also need to consider heating controls, heating system efficiency, ventilation, cooling, lighting, hot water and controls and management systems.
Battery storage and solar should not be treated as identical technologies. Solar generates electricity; a battery stores electricity for later use. Whether battery storage materially affects a specific EPC calculation depends on the assessment methodology and how the building's energy systems are represented.
From a business perspective, batteries can help increase the amount of solar-generated electricity that is used on site rather than exported, and help manage demand during periods when electricity prices are higher. For EPC purposes, businesses should have the specific effect assessed rather than assuming that battery storage will produce a particular rating improvement.
Before replacing a commercial roof to improve EPC performance, businesses should assess the existing roof systematically.
Identify leaks, deterioration, corrosion, damaged membranes and structural problems.
Determine what insulation exists, its thickness, condition and the existing deck/membrane construction.
Identify areas where heat transfer is excessive and check gutters, outlets and drainage systems.
Assess condition, thermal performance, safety and identify HVAC, vents, pipes and other penetrations.
Determine available roof area, orientation, shading and structural suitability.
Review electricity consumption, heating demand, operating hours, and study the current EPC recommendation report.
An EPC should not simply be treated as a certificate to file away. Its recommendation report can help identify potential energy-efficiency improvements. For example, the assessment may identify weaknesses in the building fabric or services. A business can then compare the recommendations with the planned capital works.
If the roof already requires replacement, it may make sense to combine the necessary roof work with insulation improvements. If the building has a large roof and substantial electricity demand, solar may also be worth assessing.
This creates a staged improvement strategy:
There is no single EPC target that applies to every commercial property. The appropriate target depends on the building, its use, location, existing construction, services and regulatory circumstances.
Businesses should also distinguish between improving energy performance and meeting a particular legal requirement. For properties in England and Wales, current commercial EPC rules and minimum energy-efficiency requirements can involve specific circumstances, exemptions and regulations. A professional energy assessor can provide building-specific advice.
Energy performance can influence how a commercial property is perceived by prospective tenants and buyers. A property with a modern roof, improved insulation and on-site renewable generation can have advantages beyond the EPC certificate itself.
However, these benefits vary by property. A strong EPC should not be viewed as a substitute for a properly maintained building — roof condition remains important because a poor roof can create water ingress, maintenance and operational problems even if the property has solar panels.
A commercial solar installation can be a significant long-term investment. The roof beneath it should therefore be suitable for the expected service life of the solar system. Installing solar on a roof that already has widespread deterioration can create a difficult sequence — the business may eventually need to remove the solar equipment, replace the roof and reinstall the solar system, creating avoidable labour costs and operational disruption.
A roof assessment before solar installation can identify whether replacement, repair or maintenance should happen first. This is particularly important for large warehouses where roof replacement and solar installation can involve substantial areas and equipment.
Energy performance and carbon emissions are closely connected, but they are not identical concepts. An EPC is an energy-performance assessment and does not simply measure the building's actual utility bills. The EPC methodology uses standardised assumptions and approved calculation methods.
Solar can support a lower calculated energy or carbon impact, while insulation can improve the thermal characteristics of the building. This distinction matters because a business may see different outcomes between actual energy consumption, energy bills, carbon emissions and EPC rating — these measures are related but should not be treated as interchangeable.
ERS Energy Ltd provides commercial roofing, solar installation and energy solutions for businesses. Its commercial roofing service covers roof replacement, TPO and EPDM membrane systems, metal roofing and cladding, roof inspections, maintenance and repairs. Its commercial solar service covers solar PV installation, energy storage, BIPV integration, smart-grid connectivity and performance monitoring.
The company combines roofing and solar assessment so that the roof can be considered before solar equipment is specified. This is particularly useful for businesses that have an ageing commercial roof, are planning roof replacement, have high electricity consumption, want to generate renewable electricity, need to improve thermal performance, are reviewing an existing EPC, or want to combine roof and solar works.
A combined project should begin with assessment rather than equipment selection. ERS Energy Ltd's process starts with a site visit and assessment. The roof is reviewed for condition and suitability, while the solar design considers available roof space and energy use. A written proposal can then outline the required roofing and solar work.
This approach helps answer key questions before installation begins:
Improving a commercial EPC rating is not the end of the project. The roof and solar system should be maintained so they continue to perform properly. Roof maintenance can identify blocked drainage, membrane damage, sealant deterioration, flashing problems, rooflight issues, structural concerns and water ingress.
ERS Energy Ltd provides planned commercial roof maintenance, inspections, condition reports and emergency repairs, including checks of solar systems installed as part of combined projects. Solar systems should also be monitored — a reduction in generation can indicate panel problems, inverter faults, electrical issues, shading changes, dirt or system degradation.
One of the most important decisions a commercial property owner can make is to review the EPC before starting major building work. Without an EPC review, a business may spend heavily on one improvement while leaving a larger energy-performance weakness untouched.
For example, a company could replace the roof but fail to address inefficient heating. Another business might install solar without improving poor roof insulation. A third property might have a strong roof and solar system but inefficient lighting and controls.
The EPC provides a starting point for understanding the building as a complete energy system. The government guidance explains that the EPC assessment takes into account building fabric and services rather than relying on one component. This means the best strategy is usually a coordinated one.
For a business considering roofing and solar, the following sequence can provide a logical starting point:
Find the property's current EPC and recommendation report.
Identify the current A-to-G rating and the areas contributing to the result.
Arrange a professional survey to establish roof condition, insulation and structural suitability.
Determine whether insulation needs upgrading and examine electricity/heating consumption.
Consider roof area, orientation, shading, structural capacity and electricity usage.
Determine the best approach (repair, encapsulation, replacement, insulation, solar) and plan together.
After installation, monitor energy consumption, solar generation and roof condition, then arrange a new EPC assessment after qualifying improvements have been completed.
ERS Energy Ltd is a commercial roofing, solar and energy-efficiency business based at Leigh Works, Bradshawgate, Leigh, WN7 1AP, United Kingdom. The company provides commercial roofing, roof replacement, repair and maintenance services alongside commercial solar installation and energy solutions.
ERS Energy Ltd works with commercial and industrial properties and states that its roofing and solar services are available across Greater Manchester, the North West and nationwide. Its commercial roofing services include TPO and EPDM membrane systems, metal roofing and cladding, roof inspections, preventive maintenance, emergency repairs and roof replacement. Its commercial solar service includes solar PV installation, energy storage, BIPV integration, smart-grid connectivity and performance monitoring.
The company assesses roof condition and solar suitability as part of its project planning, allowing businesses to consider roofing and solar requirements together. Explore our commercial roofing services and commercial solar panel installation.
For businesses looking to improve commercial energy performance, this combined expertise can be particularly relevant where an ageing roof, poor insulation and high electricity consumption are present at the same property. ERS Energy Ltd also provides ongoing roof maintenance and inspections to help protect your roofing investment.
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ERS Energy Ltd Google Business ProfileRoofing and solar can contribute to improved commercial energy performance in different ways. An upgraded roof can improve the thermal performance of the building envelope. Better insulation can reduce heat transfer and help the building maintain internal conditions more efficiently. Solar PV can generate electricity on site and reduce reliance on grid electricity.
When the two are planned together, businesses can address both the physical performance of the building and its energy generation potential.
However, there is no universal EPC improvement that can be guaranteed from a particular roof or solar system. The existing EPC, building construction, heating, cooling, ventilation, lighting, occupancy, roof insulation and solar design all affect the final result.
The most effective starting point is therefore an assessment. Review the existing EPC. Survey the roof. Check the insulation. Analyse energy consumption. Assess solar potential. Then design the improvement programme around the building rather than selecting isolated technologies.
For commercial property owners planning a roof replacement or considering solar, an integrated roofing and energy assessment can prevent incompatible investments and help identify where capital expenditure can deliver the greatest improvement.
Get a professional assessment of your commercial roof and solar suitability, and understand how to improve your building's energy performance.
