SBEM for Game Boy!

Achieving Part L energy code compliance no longer has anything to do with building energy use. Your new building energy rating is not expected to tell you what your energy use might be.

What is going on….All-Sports-Commentary

SBEM – the computer tool behind part L – has been taken over by Game Boy.  It’s now about gaming the system to achieve code compliance. It is counter intuitive and with it engineering judgement has become redundant. Innovation is stifled as it does not conform to predefined gaming rules. And the more the Part L targets are tweaked, the more the gaming features divide win from lose. The aim is solely to second guess a black box reference model to win!

Digging deeper….

By choosing the right gaming software vendor can improve your chances by 20% or more. Did you know that the A-G scale is not carbon emissions – it is a reference model comparison? Hence a key gaming feature is adjusting the reference model baseline to enhance your chances. The more you raise the reference model energy use, the easier it is to get under that target allowance. Remember that you get extra savings opportunities by adding complexity features.

 So where is this getting us….

We are now getting energy intensive heavily air conditioned buildings with better ‘energy labels’ than energy frugal passive buildings. Needless over provision of fitout systems capacity is the norm because this lifts the target allowance. It also perversely reduces the significance of longer term building fabric performance. Fitout partitions are positioned in the game to maximise perimeter room cooling gains as this also raises the target allowance. Air conditioned all-glass escape stairs and the like are provided as this lifts that target allowance. Glare, blinds down and AC continuously running are the result because the claimed daylight factor credits do not in reality make comfortable rooms. Code compliance is so divorced from reality – and the gamers know it – such that the reality of their assumptions cannot be double checked in the completed building. The complexity of code compliance means very few understand what is going on – yet real building energy use is a function of a whole string of other currently disenfranchised stakeholders.

Having spent much of the last four years working abroad I have found it fascinating coming back with new eyes and experiences to see how the UK’s leadership in this field has been side-tracked.

 So what should be done to put us back on the right track…

  • Far more transparency in Part L and SBEM – to promote continual improvement, engineering intuition, lower energy innovation and wider stakeholder engagement.
  • A single clear absolute kWh/m2.yr value as the target allowance to beat by whatever systems the designers decide – not the gaming encouraged by the comparison of similar solutions.
  • Code compliance should include predicting alternative in-use scenarios – analogous to your car consumption figures.
  • Removal of excessive fitout/unregulated energy profiles to ensure the building fabric / base systems have due priority / influence.
  • Mandate our universities to research real life feedback, identify the ‘Performance Gaps’, critique and propose continual evolution of modelling tools and real life implementation.
  • A simpler alternative code compliance route for the many simpler buildings – ie ‘Elemental’ component performance compliance for ‘deemed to satisfy, without needing project modelling.

As professionals our role is to develop solutions for the common good – not to support the propagation of system distortions. We also must be crucially aware of our liability as our end-user consumers becoming increasingly expectant that a label describes what is in the tin.


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