2 Outline Brief

Aims of Brief and Benchmarking

One of the most important aspects of any retrofitting project is how to measure a successful outcome: it is necessary to set benchmarks at the outset.

Funding for this project is not likely to be from government unless grants for heating upgrades are possible. Since the 'able to pay market' is effectively unregulated the client is able to decide which benchmarks can be set and what methodologies are employed The National Trust appears to favour the LETI Climate Emergency Retrofit Guide's approach.

It is worth emphasising that LETI, PAS2035, PHPP, Minergie, AECB and other benchmarking protocols all stress the importance of a fabric first approach to retrofitting

For this project the instructions in the architect's appointment were general: aims include 'reducing the carbon footprint', using the LETI retrofit standard, increase lettability', and installation of renewables on adjacent buildings

Since the NT are at the beginning of the retrofit 'journey it was decided that this project might explore various options for building improvements, without setting firm targets, but focusing on thermal comfort and health and wellbeing for the resident and conservation of the building

LETI Guidance

Since the client has expressed a preference for the LETI protocol it makes sense to follow the general guidance contained in the LETI Climate Emergency Retrofit Guide:

- define the project and outcomes

- understand the building and risks

- plan and evaluate improvements

- install and commission

- check and monitor outcomes

LETI targets fall into two main categories: constrained and unconstrained buildings

Since Burraton Farm is a Listed structure, constraints are assumed and EEMs would exclude improvements which would unacceptable harm the character of the buiding

For this category of building, reduced targets are deemed acceptable and are set as follows, assuming a fossil free fuel:

Energy Use Intensity 60kWh/m2 pa

DHW demand 25kWh/m2 pa

The LETI approach allows two options for compliance: calculation of EUI as above, or elemental

Since the author is qualified OCDEA SAP assessor it will be possible to calculate the effect of any improvements but the elemental guidance is also worth noting; these figures are seen as minimum values for thermal elements:

Walls: 0 32 W/m2K

Roof: 0 12 W/m2K

Floors: 0.8W/m2K

Windows: 1.3W/m2K

Doors: 1 0 W/m2 K

Air tightness: 3ac@50Pa

No fossil fuels

Renewables where possible

In order to arrive at a retrofit proposal it is important to establish the current situation as far as energy efficiency is concerned, requiring the detailed survey of the existing building

The survey should ascertain the thermal performance of the building elements, but also the whole house performance, and identifying other works which might be incorporated into any retrofit project.

In other words, to carry out a whole house retrofit, a whole house survey should be instigated The author has already provided a comprehensive list of surveys which form a basis for any project, and which may be referred to in the next stage of project development