Achieving Outstanding Thermal Performance with Low Embodied Energy Material: A Guide to Part L Compliance

At Barefoot Architects, we believe in creating homes that are not only beautiful and functional but also sustainable and energy-efficient. Whether you're building a new home or renovating an existing one, achieving excellent thermal performance is essential for both comfort and environmental responsibility. A key element of this is ensuring that your home meets Part L of the Building Regulations, which focuses on the energy performance of the building in use. By using low embodied energy materials, you can go a step further by also reducing the carbon footprint of the construction of your home.

What is Part L and Why Does it Matter?

Part L of the Building Regulations sets out the energy performance standards for buildings. It ensures that homes are designed to reduce carbon emissions through better insulation, efficient heating systems, and airtightness. Achieving Part L compliance ensures that your home is well-insulated, reducing the need for heating and making it warmer in winter and cooler in summer.

While it’s crucial to focus on operational energy—how much energy your home uses to heat, cool, and power it—the embodied energy of materials also plays an important role. Embodied energy is the energy used to produce, transport, and install building materials. Using low embodied energy materials can significantly reduce the overall carbon footprint of your home while improving its thermal performance.

Use of natural materials on a house in Bristol

How Thick Should Insulation Be to Achieve Part L?

Achieving the required thermal performance is a key part of meeting Part L. Your insulation thickness determines heat loss and maintaining a comfortable temperature. For typical insulation materials, the following guidelines are useful:

• Walls: Solid walls usually require 100-150mm of insulation, while cavity walls typically need around 100mm of insulation.

• Roof and Loft Insulation: A roof or loft should have 300-400mm of insulation to achieve Part L standards.

• Floors: Insulating floors typically requires 100-150mm of insulation.

Low Embodied Energy Materials for Thermal Performance

1. Natural Insulation Materials
   Materials such as cellulose, sheep wool, and cork are excellent insulators with low embodied energy. These materials offer great long-term thermal performance, reducing the need for synthetic alternatives that have a higher environmental impact.

2. Timber Frame
   Timber, when sourced responsibly, is a low embodied energy material that works well for both structural elements and insulation. It has a better thermal performance than traditional masonry, reducing the need for artificial heating and cooling.

3. Thermal Mass Materials
   Rammed earth, and hempcrete are materials with high thermal mass, meaning they absorb heat during the day and release it at night, keeping your home cooler in the summer and warmer in the winter. These materials can reduce the need for mechanical heating and cooling.

Woodfibre was used as internal wall insulation at our retrofit project at ‘The Swan’

Putting It All Together

Achieving Part L compliance with low embodied energy materials is not only possible—it’s a sustainable choice that benefits both your home and the environment. By selecting natural insulation materials, sustainable timber, and high thermal mass materials, you can create a comfortable, energy-efficient home while minimizing your carbon footprint.

At Barefoot Architects, we are committed to helping you design homes that balance sustainability with comfort and functionality. We’re here to guide you through every step of the process, ensuring your home is not only compliant with Part L but also designed to stand the test of time, both in terms of energy efficiency and environmental responsibility.

Let’s build a greener future, one sustainable home at a time.