3 Outline Assessment of the Building

3.1 Existing Building Construction

Burraton Farm is a C17th farmhouse which was extended in the C19th. It is currently a single dwelling although it has apparently been used as two separate dwellings

The structural walls are random slatestone rubble rendered externally on the three principal elevations and plastered internally The external coatings appear to be cementitious Internal plasterwork is a mixture of lime and gypsum Some of the walls have been panelled internally with a mineral fibre sheet covering studwork, presumably insulated voids

The slate roof appears to have been renewed in the last 15 years. The roof structure is in good condition The traditional lime parging has been replaced with impervious bitumin based roofing membrane

The windows are modern cottage style single glazed painted timber units and recently installed The external doors are solid timber boarded doors.

The ground floor was not possible to investigate but is assumed to be a solid floor, probably stone flag on rammed earth on the original farmhouse but now covered with a modern surface.

The upper floor is traditional timber boards on joists with plaster ceilings.

Heating is from a mix of storage heaters and oil radiators There are also two open grate fires, and a disused gas fire Water heating and storage is an insulated cylinder with electric immersion

Electrical circuits are partially surface mounted. There appears to be two circuits and one may be E7 off peak

There is one intermittent fan in the kitchen

It is recommended that a more detailed survey is carried out to ascertain the exact nature and condition of the ground floor, the electrical circuits, and structure generally. It is also recommended that an air pressure test is carried out, along with a Radon level test page 4/8

3.2 Patent Defects

Loft insulation has been inconsistently added and appears to be blocking eaves vents. SInce the main roof is hipped this will stop any cross ventilation and use of non porous felts prevent moisture migration Since the roofspace is poorly ventilated there is consequentially significant amount of condensation on the underfelt which could lead to degradation of the roof structure and cause damp on ceilings

The cement dash coated external walls prevent the building from breathing and contribute to moisture penetration via the cracks in the render finish The consequential build up of moisture on internal surfaces is apparent, exacerbated by lack of ventilation and inadequate heating

Condensation is particularly noticeable on windows and at cold bridges leading to mould growth and degradation of finishes

Attempts have been made to improve the situation, eg, addition of flooring with thicker underlay

CAVEAT: this section of the report is not intended to be a condition survey and further investigations are recommended particularly in regard to insect and fungal attack

3.3 Current Performance

Burraton Farm is a traditional farmhouse, which has been subject to typical and well meaning building maintenance over the years

Sadly some treatments have led to a deterioration of its condition and performance: the application of cementitious renders and gypsum based plasters; the use of non porous roofing felt; the blocking of roof ventilation; all contribute to entrapment of moisture in the building s fabric.

A lack of ventilation, combined with an inadequate heating system (the storage heaters are not sufficiently large to keep the building properly and consistently heated, even when combined with the open fires) which fails to keep internal wall surfaces warm, provides the conditions for condensation on internal surfaces which encourages mould growth

In terms of energy efficiency measures, and always assuming a fabric first approach, priority needs to be given to - improve the insulation properties of the building elements - improve ventilation to encourage mositure migration - improve the delivery of heat energy to the speces

Bearing in mind that the property is Listed, these EEMs will need to be discreet and where possible, be combined with other scheduled building works, including maintenance where deemed necessary

Any future improvement works whether or not EEMs are introduced, should include measures to improve ventilation and heating, in order to reduce or remove damage to finishes and which will safeguard the health and well being of the residents.

3.4 Energy Assessment

The building has been the subject of a RdSAP DEA and achieves a EPC E 43

It is important to understand the limitations of the RdSAP methodology which essentially makes broad assumptions on properties which are older than 1900.

Using the RdSAP for any other purpose than asset management might be considered to be misguided: in the opinion of this author RdSAP is not the best basis for retrofit design For example: the DEA would not take into account the size and capacity of the electric storage heaters The fact that heaters are present does not mean that the house is adequately heated

A quick calculation (below), assuming an AC rate of 1 5ac/h and a temperature difference of 20oC, gives a steady state heat loss of around 15kW.

Since the total capacity of the electric heaters is around 8-9kWand these will lose capacity as the storage 'battery' runs downthe occupant will need to rely on open fires for comfort. An open fire generally loses up to 70% of heat energy up the chimney.

It can be appreciated that the current situation is not ideal: the building needs consistent heating to maintain comfort, control moisture, and to protect the building fabric.

By comparing the values in this table with the LETI outline targets it can be appreciated that the thermal elements and ventilation targets need to be addressed

The print out below from the SAP calculation highlights the issues, and suggest that the only element which is within reasonable limits is the roof insulation

Energy Usage

By using SAP to calculate the outputs (in accordance with LETI guidance) we find following values:

The EUI is : 155kWh/m2 pa: three times the LETI target

The cost of heating the property for thermal comfort is a significant proportion of any rental: this figure needs to be seen in the context of huge energy price increases but also the effect on the building of intermittent or poor heating.