What is the minimum EPC rating for commercial buildings?

Since April 2023 it is unlawful to let a commercial property in England and Wales with an EPC below E. The government has consulted on raising this to C by 2027 and B by 2030, though the final timetable has not been confirmed.

Does secondary glazing improve an EPC rating?

Yes. Secondary glazing is recognised in the SAP and RdSAP assessment methodologies and typically improves window U-values from around 4.8 to 1.8 W/m2K or better. It is often the only approved option for listed buildings and conservation areas.

How much does lighting contribute to building carbon?

Lighting accounts for roughly 20 percent of electricity use in UK commercial buildings. Switching from fluorescent to LED with occupancy and daylight controls typically cuts lighting energy by 50 to 70 percent with paybacks of two to four years.

Fabric-first carbon reduction

Building Energy Efficiency and Carbon Costs

Heating and powering buildings is one of the largest sources of UK emissions. Improving the fabric and systems of a property lowers energy bills, cuts reported emissions and reduces exposure to carbon pricing passed through in energy costs.

Estimate Your Carbon Costs Window & Glazing Grants

Why buildings matter for carbon pricing

Carbon costs reach building owners indirectly. Electricity generators and large heat producers pay for allowances under the UK ETS, and that cost is reflected in the tariffs businesses and households pay. The less energy a building uses, the smaller that exposure.

Regulation adds a second driver. Commercial landlords in England and Wales must meet Minimum Energy Efficiency Standards (MEES) to let a property, and larger companies report energy use and emissions under SECR. Fabric improvements help with both.

A fabric-first approach, reducing the heat a building loses before upgrading the plant that supplies it, is generally the most cost-effective order of work. Windows, particularly single glazed windows in older stock, are a common weak point.

Where to start

Get an up-to-date EPC or energy audit to establish a baseline
Address heat loss through windows, roofs and draughts first
Replace remaining inefficient lighting
Install controls so systems only run when spaces are occupied
Meter and monitor so savings can be evidenced in reporting
Consider heat pumps once demand has been reduced

Key efficiency measures

Three categories of upgrade that consistently reduce energy demand across residential and commercial buildings.

Secondary glazing

An independent internal pane fitted inside existing windows. It reduces heat loss through single glazing without replacing original frames, which is why it is widely used in listed buildings and conservation areas where replacement windows are restricted.

Lower heating demand
Retains original windows
Also reduces external noise
Typically permitted in heritage properties

Efficient lighting

Lighting is one of the simplest loads to cut. Replacing older incandescent, halogen or fluorescent fittings with modern low-energy alternatives reduces electricity use and the Scope 2 emissions that go with it.

Immediate electricity savings
Reduced maintenance
Counts towards SECR reporting
Low capital cost

Smart controls and monitoring

Zoned heating controls, occupancy sensing and energy monitoring let building operators see where energy goes and stop heating or lighting empty space. Measurement is also the first step in any credible carbon reporting exercise.

Visibility of consumption
Avoids heating unoccupied rooms
Supports carbon reporting
Behavioural savings

Specialist suppliers and further reading

TaxCarbon provides guidance on carbon costs rather than installation. The following specialist providers cover the practical measures discussed on this page.

Secondary glazing specialists

Specialist installers who supply and fit secondary glazing to reduce heat loss and noise in period and listed properties.

Noise reduction glazing

Acoustic secondary glazing addresses both thermal performance and sound insulation, relevant for urban commercial premises near roads, rail or flight paths.

Lighting and home energy

Resources on low-energy lighting and smart home technology for monitoring and reducing household energy use.

Related guidance

Building efficiency sits alongside construction emissions, reporting obligations and the wider net zero transition.

Embodied Carbon in Construction Net Zero Guide

Frequently asked questions

What is the minimum EPC rating for commercial buildings?: Since April 2023 it is unlawful to let a commercial property in England and Wales with an EPC below E. The government has consulted on raising this to C by 2027 and B by 2030, though the final timetable has not been confirmed.
Does secondary glazing improve an EPC rating?: Yes. Secondary glazing is recognised in the SAP and RdSAP assessment methodologies and typically improves window U-values from around 4.8 to 1.8 W/m2K or better. It is often the only approved option for listed buildings and conservation areas.
How much does lighting contribute to building carbon?: Lighting accounts for roughly 20 percent of electricity use in UK commercial buildings. Switching from fluorescent to LED with occupancy and daylight controls typically cuts lighting energy by 50 to 70 percent with paybacks of two to four years.

Have a question we haven't covered? Get in touch or browse the carbon glossary.