In 2022, the UK building regulations were updated, setting new benchmarks for the thermal performance of buildings. These updates aim to improve energy efficiency and reduce carbon emissions, a crucial step towards a more sustainable future. The revised Part L documents specify minimum U values for new constructions and renovations. The focus is on three key components: roofs, walls, and floors. Achieving these U values is essential for compliance, but it raises the question: how much insulation is needed to meet these standards?
To address this, we’ll explore the required thickness of three popular insulation materials: Expanded Polystyrene (EPS), Rockwool, and Kingspan K5. Each material has its unique properties and efficiency ratings, which influence the thickness needed to reach the desired U values.
Current regulations – New Constructions
For newly built structures, the updated regulations have set the bar higher for energy efficiency, with stricter U values as follows:
• Roofs: 0.11 W/m²K
• Walls: 0.18 W/m²K
• Floors: 0.13 W/m²K
These values are designed to ensure that new buildings are constructed with optimal insulation, minimising heat loss and reducing energy consumption.
Renovations present an opportunity to bring existing buildings up to modern standards of energy efficiency. For new elements introduced in existing dwellings, the regulations specify:
• Roofs: 0.15 W/m²K
• Walls: 0.18 W/m²K
• Floors: 0.18 W/m²K
These requirements are slightly less stringent than those for new constructions, recognising the challenges and limitations that can come with upgrading existing structures.
For existing elements within existing dwellings, the regulations provide limiting U values, setting a baseline for the minimum acceptable level of insulation:
• Roofs: 0.16 W/m²K
• Walls: 0.30 W/m²K
• Floors: 0.25 W/m²K
These values are more lenient, acknowledging the practical difficulties in retrofitting older buildings but still pushing for improvements in energy efficiency.