In this two-part series of articles, we’ll investigate how architects can optimise their designs to respond to the pending changes in Part L Building Regulations between 2014 and 2020, using a phased project in Leyton, East London.

In order to comply with 2014 regulations, our design needs to be adjusted to achieve a 9% reduction compared to 2010 acceptable carbon emissions. We will test scenarios with different envelope options, HVAC systems & efficiencies,  as well as low carbon technologies, such as solar PVs and and Solar Thermal Hot Water Systems,  to see which single and combined variables help us reach our goal.

In this first part, we carry out performance analysis on a non-domestic new build project which already meets 2010 Part L requirements. Our ensemble is made up of a city hall, concert hall and theatre, on the fringes of the Olympic Village.




Baseline Concept

To reach a 9% reduction, our annual CO2 production needs to fall from 1,398, 901 kgCO2 to a value below 1, 272, 999 kgCO2.



Once imported into Sefaira’s web app, a first round of analysis reveals that our building is susceptible to high solar gain and that it loses heat through ventilation and conduction.




With this knowledge, we are now able to make relevant adjustments to the design to improve its performance at an early stage. In this instance, we’ll focus on the fabric, glazing, solar shading and HVAC system efficiency.


Improving Design Performance


Our next step is to test single improvement Strategies to see what impact they have on the design.

Strategy 1. Figure 4 shows that specifying more efficient fabric properties such as the facade and roof glazing U Factors, the solar heat gain coefficient, the wall U Factor, air leakage, and surface reflectance  gets us a 5% reduction.

Strategy 2. Glazing Ratio & Solar Shading adjustments offers approximately 1% savings in carbon emissions.

Strategy 3. Adding a Mechanical Ventilation Heat Recovery System that operates at 70% efficiency contributes a 9% saving to the baseline.





It is safe to assume that adjusting the glazing ratio and applying solar shading are the two strategies that have the least impact on our design. Adding an Mechanical Ventilation Heat Recovery System appears to be a crucial strategy; it offers a 9% reduction in carbon emissions- almost significant enough to make it a stand-alone measure.


Combining Strategies

It is essential to check the combined effect of different strategies as you cannot always expect an additive outcome. This calculation is made possible by Sefaira’s Bundle option. In this example, we tested several combinations. The most rewarding bundle is a fabric, glazing and shading upgrade as well as the addition of a MVHR system.

A combined 13% reduction in Annual CO2 Production goes well and beyond the 2014 requirements for meeting Part L.



Armed with Sefaira’s building physics analysis tool, it is now possible for designers to rapidly and accurately test and adjust their designs in response to unforeseen regulation, brief or budget changes.