A bit of reading required if interested. Bottom to top.


Thanks for confirming that Christian

Please find enclosed the design stage calculations for this new dwelling based upon the thread below

FAO Building Control

In reference to the new dwelling I would confirm that on this particular build a Low and zero carbon feasibility assessment with regards to high efficiency alternative heating systems for the development has been carried out

In this instance the developer has not incorporated any low and zero technology in this dwelling – instead they have provided a very well insulated building fabric to actual reduce the energy needed to condition the environment.

Items such as wind and hydro were dismissed on the grounds of applicability for the location.

Solar thermal was looked at but the returns were not high enough to make it economically viable.

The most logical solution was to provide a PV array to the house which would give a better reduction in C02, however it wasn’t chosen at this stage. This is something that is easy to retrospectively install however if it is so desired by the client.

Please do not hesitate to contact me if I can help further

Kind Regards

Stuart ***

Hi Stuart,

That’s great thanks and yes all of your points appear to be correct. It would be good to know if it would still pass using more of a medium density block for the inner leaf, because I have heard one or two moans from builders about the thermalite blocks?

Best regards,

Christian Simmons


Hi Christian – apologies again for the email problems - I have prioritised this one for you Thank you for your instructions to produce the design stage SAP for your new dwelling. Before I can finalise the report, please can you confirm that the specification below is what has been proposed for the dwelling

Ground floor – Screed on 100mm Celotex on a slab to achieve a U value of 0.15W/m2k

Walls: rendered masonry dense block outer leaf, 50mm cavity with 50mm Celotex insulation and a 100mm thermalite block inner leaf insulated to achieve a U value of 0.25W/m2k

Roof (flat roof) 130mm Celotex fitted over a warm deck to achieve a U value of 0.17W/m2k

Windows – triple glazed alluminium units with a U value of 1.0W/m2k

A design air permeability rate of 4 has been used.

5No. mechanical extract fans will be provided to the dwelling

A mains gas fired system boiler will heat the property feeding an underfloor heating system controlled via a time and temperature zone control system. The boiler will be equipped with an interlock and a delayed start thermostat. In my calculations I have used a Worcester 30CDI System model.

A 300litre hot water storage tank has been used.

All installed lighting will be energy efficient · The builder will follow accredited construction details on site to reduce the risk of thermal bridging. A schedule of junction details should be provided to the developer to abide to on site and then sign upon completion as confirmation that he followed them. Heres a link

To combat the risk of solar overheating in the summer, the windows will be dressed with curtains or roller blinds.

On the basis of the above, I’m pleased to say that the scheme passes the fabric efficiency criteria of the Building Regulations and the DER/TER without the need supplement the scheme with any renewable energy.

Please do not hesitate to get in touch to discuss any of the above once you have had chance to look at it.

Once you can confirm the above we can issue the design stage calculations for you Kind Regards Stuart *** Hi Stuart,

How are you, well I hope?

Please find attached Detailed Drawings for the new build project for Tamsin Maund and Chris Webber at Aucklands, St Ives Road. My intent6ion was to use Keystone Hi-therm lintels throughout. Could you please carry out a SAP Rating on the project and send your invoice to Tamsin at

Best regards,

Christian Simmons