U-Value and EPC Explained

Miles Procter
9 October 2024
FREE DOWNLOAD
Get the CosyPanels Brochure

Discover how CosyPanels can turn your conservatory into your dream living space

Cosypanels brochure mockup
EPCs provide a clear picture of a property's energy use and efficiency, making them an essential consideration for anyone looking to buy, sell, or rent a home. Understanding how U-value and EPC work together is the first step towards building houses that are more sustainable.
Polycarbonate conservatory roof

Table of Contents

In today’s world, energy efficiency in our homes is more important than ever. Not only does it contribute to a reduction in carbon emissions, but it also offers significant financial benefits to homeowners and landlords alike. One crucial aspect of assessing a home’s energy efficiency in the UK is through Energy Performance Certificates (EPCs). These certificates provide a clear picture of a property’s energy use and efficiency, making them an essential consideration for anyone looking to buy, sell, or rent a home. Understanding how U-value and EPC work together is the first step towards building houses that are more sustainable.

Why EPC is important:

Energy Performance Certificates (EPCs) are more than just a bureaucratic requirement—they can significantly influence the market value and appeal of a property. For homeowners aiming to sell, achieving an EPC rating of A or B can boost the property’s sale price by up to 14%. Meanwhile, landlords face the pressing deadline of 2028 to ensure that their properties meet at least a C rating or risk fines of up to £30,000. Beyond the legal and financial incentives, improving EPC ratings can lead to substantial savings on energy bills, an attractive benefit for current homeowners looking to reduce monthly expenses.

The investment in improving a property’s EPC rating is not trivial, with an average outlay of around £25,000 needed to bump a rating up by two letters. However, strategic improvements, particularly involving the insulation properties of building materials, can make a significant difference.

  • Homeowners looking to sell their properties will find that getting their EPC to A or B can add up to 14% to the sale price
  • Landlords renting their properties have to make sure EPC rating is at least C by 2028. Penalties for non-compliance will be up to £30,000
  • Homeowners who’ve settled in their current property will make significant savings on gas and electricity bills by improving their EPC performance
  • Average amount of money spent to increase EPC rating significantly (at least by 2 letters) is £25,000

A good strategy for achieving a substantial improvement in EPC is to be mindful of insulation properties of materials used in refurbishment that’s why we look at U-value and EPC as two closely intertwined concepts.

Difference between the U-value and R-value

U-value measures the insulating performance of a material, in other words – how much heat loss occurs, whereas R-value measures the thermal resistance of an insulation material or how resistive the material is to heat loss. The correlation also explains the reciprocal nature of the two measurements. The lower the U-value, the better the performance, and the higher the R-value, the better the material’s performance.  This is why, when it comes to improving EPC, it’s important to focus on materials with low U-values and high R-values.

A factor that affects the U-value and R-value of an insulation material is its thickness. Generally, the thicker the material, the lower the U-value and the higher the R-value.

U-values of specific materials

Understanding the U-values of specific building materials is key to making informed decisions about home improvements. U-values measure how effective a material is as an insulator, with lower values indicating better insulation properties. For example, single glass has a U-value of 4.8 W/m²K, while more advanced options like triple glazing with thermal coating can bring this down to 0.8 W/m²K. Similarly, materials such as solid roof tiles boast low U-values of 0.15 W/m²K, making them excellent choices for reducing heat loss.

  • Single glass – 4.8 W/m²K
  • Double glazing – 3.0 W/m²K
  • Triple glazing – 1.8 W/m²K
  • Triple glazing with thermal coating – 0.8 W/m²K
  • Solar control glass – 0.5 – 1.0 W/m²K
  • Thermal blinds – 2.00 W/m²K
  • Conservatory roof panels – 0.24 – 0.29 W/m²K
  • Polycarbonate roof panels – 1.6 -2.1 W/m²K
  • Solid roof tiles – 0.15 W/m²K
  • Slate roof – 0.9 – 2.0 W/m²K
  • Brick wall – 2.0 W/m²K
  • Concrete wall – 1.75 – 2.25 W/m²K
  • Timber – 1.2 – 1.4 W/m²K

Quickest and cheapest ways to improve your EPC rating

For those looking to improve their EPC rating quickly and affordably, there are several effective strategies. Switching to LED lighting is a low-cost option at around £20, while loft insulation can be implemented for £600 to £1,000. More extensive measures, such as insulating a conservatory (£3,000 – £5,000) or upgrading to triple-glazing windows (£5,000 – £7,000), provide significant insulation improvements and boost EPC ratings considerably.

  • Replace lighting for LED bulbs – £20
  • Loft insulation – £600 – £1,000
  • Insulate your conservatory – £3,000 – £5,000
  • Replace your windows with triple-glazing – £5,000 – £7,000

Improving your home’s EPC rating is not just about compliance with regulations—it’s an investment in the property’s value and energy efficiency. Whether you’re a homeowner looking to sell or a landlord needing to meet new standards, exploring options like advanced glazing and effective insulation can bring substantial rewards. Take the first step towards a more energy-efficient home and consider how these enhancements can benefit your property and your pocket.

U-Value and EPC Infographic

U Value EPC Infographic