Part L, Passivhaus, your design team and other observations…

This is a bit of a continuation on the last blog post that threads together a few observations on Part L, building economics and your design team.

Observation 1. Part L:

What’s interesting about the recent Part L changes is that rather than just thinking about u values for each element, you now need to think holistically about the entire building. As an example, Part L now gives detailed advice on the percentage of glazing in relation to floor area. Below from table 2 you can see that with a u value of 0.8 W/m2K, the maximum permitted combined area of external doors windows and footlights is 58.9%.


Now this is very specific and has a range of consequences that I’ll discuss in the next observations:

Observation 2 – Working closely with DEAP and a BER Assessor

What this means therefore to get to the 60% improvement on the 2008 Regulations (a A3 BER rating) is that the architect is going to really know his way around DEAP (ahem) or work very closely with a BER assessor. And this working closely means working at a much earlier stage of the project and to completely follow through with the project, adjusting the calculations as necessary through to the completed BER certificate in order to achieve what is a more challenging rating.

Observation 3 – Getting the team right and compliance with Part L

I’ve spoken before on the importance of getting the best team around you on your building project. This is now more important than ever with increasing standards and higher levels of litigation occurring. In summary, here’s the team I’d recommend; obviously there may be some overlaps where team members hold the correct qualifications and the list is a minimum and not exhaustive:

1. The Architect, even though I’ve said previously that architecture is becoming more of a physics test, we still need the architectural input that gives a project design quality and relevance.

2. The Structural Engineer

The architect and structural engineer should be working together to create an elegant architectural AND structural solution. More importantly, as mentioned above, you, as architect needs to think “am I qualified to undertake this role”. It’s very easy to think that a specific job doesn’t require a structural engineer, or that the builder can work out the foundations or structural sizings for you. If something goes wrong, who is going to get the blame, the builder who isn’t qualified in this area or the architect with a nice level of insurance to dip into.

3. The Quantity Surveyor

As discussed above, in order to comply with Part L, there is (and this is only one example), the windows need to be of a specification for a specific wall/floor area. Now this has big repercussions on cost; there’s a big difference between a window of u=0.8 (ie Passivhaus standard) and a standard double glazed window. Therefore, as I’ve previously blogged, the QS is required on even the most modest of budgets and at a much earlier stage.

4. The BER Assessor

See above.

Observation 4 – The architect needs to get tougher on compliance certificates:

The architect will therefore need to be involved from beginning to end if certificates of compliance with Planning and Building Regulations are required. Can you see the problem with self-builders for example where with so little money available from the banks it would be very easy to reduce the specification of the thermal envelope in order to meet the money that’s available. The architect therefore needs to be on his/her toes to ensure that the building is still compliant when any specification is reduced. And if it’s not compliant then take a stand and refuse to issue the compliance certificate.

Be careful, it’s a jungle out there! Written on the 2nd day of the budget from hell. Comments as always welcome…

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