the building regs: six months on...

Capita Symonds’ Daniel Raymond, Adam Sherburn and Margherita Cesca discuss the impact of October’s changes to the Building Regulations on the ‘Conservation of fuel and power’…

Daniel Raymond, Sustainable Engineering Design Consultant: “Part L 2010 sees a strong emphasis on the efficiency of design and requires optimised solutions to ensure all criteria along with general environmental principles are met. In essence a balance between Part L 2010 and environmental conditions such as daylighting and ventilation requirements should be sought.

Concept design stages are thus paramount in advising on the correct form of the building, allowing the design from these early stages to cope with the stipulations of Part L 2010. In doing so this will help guarantee compliance as the design develops. Essentially Part L 2010 is already embedded in the design process, fundamentally leading the design and ensuring the highest levels of energy efficiency are incorporated within all aspects of the design.  

A key example of how Part L 2010 has penetrated the design process is Criterion 3 ‘Limiting the effects of solar gains in summer.’ This condition aims to reduce the actual amount of solar gain entering a space, whether air conditioned or not, and is in addition to minimising the effects of overheating, as per previous building regulations. This ensures a key component of overheating is dealt with, rather than simply providing a means to alleviate elevated temperatures. This leads to more energy efficient solutions as by reducing solar gains entering a room, ventilation and cooling systems may be reduced in capacity, saving energy and carbon. 

Within Part L 2010 the carbon emission factor associated with grid electricity has been increased. This places an even greater focus on reducing carbon emissions by targeting electricity consumed by lighting and ventilation systems. As an example of the difficulty faced, the ‘benchmark’ building (notional building) utilises top of the range lighting along with ventilation provided by the most efficient commercial fans. As such fans need to be specified with low specific fan power and all supply and extract ventilation systems shall utilise highly efficiency heat recovery units.

Finally, as daylight control sensors could significantly reduce the power consumption of artificial lighting and hence reduce the emissions within Part L 2010 analyses, daylighting must also be computationally simulated as part of environmental studies. Ideally an optimised window design should be sought as a balance between average daylight factor’s and solar gains. It is imperative to remember that improved daylight factors allow for the reliance on artificial lighting to be reduced, which within itself holds the key to substantial energy savings. Daylight and occupancy sensors will help deal with reducing unnecessary artificial lighting, as will focusing on ways in which the building is operated.”

 

Adam Sherburn, Façade Engineering Specialist: “The impact of Part L 2010 is still to be fully realised in the design and detailing of architectural facades, with many large projects still working to the 2006 Part L regulations; the next few months will be key for the industry to fully develop working strategies in order to ensure compliance.

Many of the changes to Part L 2010 are having a significant impact on the architecture and building services philosophies, with the façade designer required to find unique solutions to the problems already under the spot light – over heating, air leakage and interface design.

A key area of change has been the focus on heat loss through interface design locations; section 5.7 of L2A 2010 sets specific methodologies for interface design. Driven by the general improvement in U value performance the industry has recognised that as the general fabric improves the performance of interfaces becomes paramount in external envelope performance. The 2010 regulations allow for three main approaches:

• Compliance with approved standard details
• Submission of project specific calculations for linear heat loss in line with BR 497
• Assumed poor performance levels in the thermal modelling Part L software.
  

The use of standard details has widely been accepted in the residential markets where construction detailing is often similar from project to project. Commercial projects will have to review the use of standard details closely ensuring that the potential impact on architecture is minimised and allow for a variety of design solutions. It should be noted however that even on the most exclusive and unique of designs many standard details are already in use by the construction industry so the change may not be a fundamental difference in approach.

The focus on designed interfaces and the requirement for ever lower air leakage rates may also drive designers, specifier’s and constructors to a more fully engineered solution and move away from a more traditional package procurement strategy.

In conclusion as highlighted by all of the comments the key to success will be in a concept design that has energy performance at is very core, from site orientation to construction detailing all aspects are now critical to compliance.”

 

Margherita Cesca, Sustainable Design Architect: “Since the implementation of the new Part L regulation, the architect’s position has become increasingly challenging. The architect has to re-think and re-consider the approach to the design process. They need to collaborate with M&E engineers and sustainability champions from the early stage of the design process, such as RIBA Stage A and B. In order to reduce costs related to the conservation of energy in buildings, surveys and studies related to Part L, a low and zero carbon report should be carried out during feasibility study. This can dramatically influence the design, orientation and layout of the building itself.

By making sure that all the environmental assessment and Part L reports and calculations are completed at RIBA Work Stages B & C, the risk to the project is minimised and better results in terms of sustainability and good design can be achieved. Ultimately, there is a better opportunity to investigate and analyse better options and satisfy the client requirement and the government building regulations’ requirements in a constructive and sustainable methodology at the earliest point, rather than the latest.”