A guide to Part L of the Building Regulations 2022

What are the Building Regulations 2022?

The Building Regulations 2022 were an amendment to the Building Regulations of 2010. Much of this latest law includes changes in response to the Grenfell tragedy, e.g. fire classification of building materials. However, the main thrust of the changes appeared under 'Conservation of fuel and power', which mainly concerns the energy performance of new and existing buildings.

One of the key changes implemented within the Building Regulations 2022 is the requirement for new homes to produce 31% less carbon emissions than current carbon emissions, and new non-domestic buildings to produce 27% less carbon emissions.

What's Part L?

Part L deals with energy performance, setting standards for energy efficiency in both new and existing buildings, both domestic and non-domestic.

Key requirements of Part L include:

• Energy efficiency assessments: A comprehensive assessment of the building's energy performance must be carried out before construction begins

• Energy performance targets: Building designs must meet specific energy performance targets, which vary depending on the building type and location

• Energy efficiency measures: The building must incorporate energy-efficient features such as insulation that meets the required U-value standards, efficient heating and cooling systems, and low-energy lighting

• Renewable energy: In certain cases, the building may be required to include renewable energy sources like solar panels or wind turbines

• Compliance verification: Once the building is completed, it must be verified to ensure compliance with Part L requirements

The overall goal of Part L is to promote sustainable building practices and reduce the environmental impact of new construction.

So does it only affect domestic housing?

No. There are two volumes to Part L, and Volume 2 covers buildings other than dwellings:

• Approved Document L, Conservation of fuel and power, Volume 1: Dwellings

• Approved Document L, Conservation of fuel and power, Volume 2: Buildings other than dwellings

What's a U-value?

A U-value is a measure of a material's ability to conduct heat. The lower the U-value, the better the insulating properties of that material - meaning less heat will escape.

Part L of the Building Regulations 2022 sets out minimum standards of U-values for different aspects of construction, such as roofs, walls, and rooflights. This now means that construction must comply with these minimum U-value standards.

So how do you achieve compliant U-values?

Generally, it's down to the insulation used, and the thickness. However, if you're fixing back insulation using fasteners, then they also become part of the U-value calculation, as they can transmit heat to the outside of the building.

As a fastener manufacturer, we would always recommend using stainless steel components to install rainscreen or cladding panels, as these consistently give lower U-values, meaning you can use thinner insulation to achieve a lower U-value, decreasing your overall cost for the project.

The same applies to using tube washers within flat roofing applications.

Can I not use carbon steel fasteners, surely that's cheaper than stainless steel?

You're right, carbon steel fasteners are cheaper - but you'll pay for it in the long run. Carbon steel doesn't have the same properties as high grades of stainless steel, meaning the combination of stainless steel and a thinner insulation panel to achieve a compliant U-value, no longer applies.

If you're using carbon steel fasteners, the U-value will increase, which means you'll have to increase the thickness of the insulation (or panel), to achieve the same compliant U-value. Overall, purchasing thicker insulation is likely to result in costly material increases, even though you may have saved a few pennies using carbon steel fasteners.

So it's a question of what combination you'd rather: more expensive, thicker insulation and cheap carbon steel fasteners, or thinner insulation and quality stainless steel fasteners?

What can I do to ensure I'm compliant under Part L of the Building Regulations 2022?

If you're a specifier:

• Design for energy efficiency - incorporate energy-efficient design principles into building plans, e.g. selecting materials with suitable U-values, optimising building orientation for natural light and ventilation, and specifying efficient heating, cooling, and lighting systems

• Consult with experts: Seek advice from energy consultants or sustainability specialists to ensure Part L compliance. They can provide guidance on best practice, material selection, and compliance verification

• Utilise design tools: Employ design software or tools that can assist in assessing building energy performance and identifying areas for improvement within the design of the construction

If you're a contractor:

• Ensure your design and planning stage incorporates energy-efficient features, such as adequate insulation to meet compliant U-value standards, renewable energy sources, and efficient heating and cooling systems

• Follow best practices during construction, including correct insulation installation, airtightness measures, and the use of energy-efficient materials

• Post construction, obtain the necessary certifications to confirm compliance - e.g. a Building Control Certificate (BCC), and an Energy Performance Certificate (EPC)

Please note that other legal requirements must be taken into consideration, such as fire regulations.