4 Outline Recommendations

4.1 Discussion

When specifying energy efficiency measures a whole house approach should be followed. Any interventions planned should be seen as part of an overall building improvement plan. In this case, which is typical of historic properties, occupant health and well being is inextricably linked to that of the building itself

Clearly improvement works have to be affordable and the client has stated that funding for improvements is limited and in proportion to rental yield value

In the absence of any previous occupant available for interview it is not possible to form an opinion on how 'lettable' the property is in its current state However the importance of thermal comfort and the health and well being of tenants cannot be overstated, and it is clear that the building falls short of modern requirements. The calculations indicate that lettability is compromised by the cost of energy

Future MEES legislation is likely to increase the minimum requirements for EPCs in rented properties so it makes sense to provide an overview of recommended works which can be undertaken as and when funds and/or occupancy allows

Without detailed survey data it will not be possible to make detailed recommendations or carry out accurate modelling but the diagram opposite illustrates the type of works needing to be carried out It is clear that most of the work is best done whilst the property is unoccupied, but some may be phased for later execution or when funds are in place

The study commissioned by the client from Community Energy Plus makes recommendations based on RdSAP values and mostly are concerned with energy delivery rather than fabric efficiency.

Funding options are limited due to the need for tenants to have income assessed and this will limit interventions possible during occupancy Nevertheless, and in the opinion of this author, it more important that the fabric of the dwelling is improved before any alternative heating measures are introduced, especially if carbon reductions are part of the aim page 6/8 increase roof ventilation block flue and insulate increase roof insulation to 400mm roof ventilation PPV or MVHR secondary glazing internal wall insulation insulate floor UFH

Cross Section Through Farmhouse

(C19th outrigger)

NTS

EEMs Considered

The main problem in properties of this type is the ground floor: the poor insulation and in this case the difficulty in installing perimeter insulation due to retaining structures means that excavation and replacement of the floor is recommended This will faciliatate UFH and electric routing

Upgrading wall construction externally will not be easily achieved due to its Listed status so IWI is recommended The application of insulated boards will allow the LETI target U value to be achieved

Retaining Wall redistribute loft insulation provide adequate roof ventilation wall insulation in roof void upgrade loft hatch check sw drains renew solid floors with insulated floors and UFH

This will not be the case with the single glazed windows: the least costly here is the installation of secondary glazing in line with the IWI although it might be possible to install replacement units at some point with low profile double glazed units which are acceptable to the LPA.

The key factor after the heat supply upgrade will be the improvement of ventilation. Attention will need to be paid to air tightness and the introduction of PIV or MVHR units.

Easier improvement will be the increase in loft insulation.

4.2 Effects of EEMs

Negelecting fabric improvements will mean that the energy required to maintain thermal comfort and reduce moisture build up will always be excessive

WIthout detailed survey data and knowledge of budget capability it is not possible to make accurate predictions about the effects of retrofit works but the tables left show that in order to meet both the energy efficiency aims of the project and the reduction of carbon footprint some or all of the following measures are needed:

- energy efficient heating combined with low temperature outputs

- thermal element upgrades including insulated floor, internally insulated walls and roof, secondary glazing

- mechanical ventilation strategy to feature positive pressure fan with heating element or MVHR and extract fans from wet rooms

The design of the technical installation is the subject of a separate commission but the principles are practical given that the works described would dovetail with the upgrading of internal finishes and services before returning the property to the market

If the complete package of measures is applied then the SAP calculation predicts an uplift of the property to a EPC C64

4.3 Broad Brush Calculations

The EUI is : 60kWh/m2 pa

DWH is: 2790 kWh pa both of which just about meet the LETI target

The cost of heating the property is a much more reasonable amount in proportion to the size of the building, but this criterion is one which might be the subject of a more different approach, see overleaf

It is also interesting to note how the addition of pvs may make a significant difference to the project in terms of energy usage However, it is important to note that whilst carbon offsetting is increased, the substitution of renewable energy generation for building element EEMs would likely have a negative impact on the thermal comfort of the occupant

4.4 Further Retrofit Possibilities

It is worth considering dividing the property into two separate lets This will

- increase lettable income and may provide additional funding for retrofitting works

- increase energy efficiency by the fact that the units are smaller, require less heat because the party wall is considered to have a zero U value

- facilitate a phased approach

Obviously the cost of separating services and arranging utility connections will need to be taken into account but the solution is more likely to result in tenancies which are affordable to heat and consequently will contribute to the health and well being of the tenants and the building itself

The division of the two properties along the original external walls will provide the best fire proofing and acoustic separation

There is clearly more work required to optimise the solution but the plans indicate that spatially the proposals provide realistically generous accommodation.

Since the dwelling was divided into two properties previously the LBC should be achievable.

The results of preliminary calculations are shown opposite.

Unit 1

2B4P House

122m2

Unit 2

1B2P House 77m2

4.5 Results of Draft Calculations for Two Semi Detached Units

The basic calculations for splitting the property into two units have an immediate upward effect on the energy efficiency of the dwellings The base EPC for two semi detached properties is two points higher than for a detached property

Installing similar EEMs to the detached example we obtain the results indicated by the tables right:

UNIT 1

EPC of C is obtainable

EUI = 44 kWh/m2 pa

Annual heating costs around £1050

Potential for reducing this to less than £250 pa with the addition of a 4kW pv array

UNIT 2

EPC of C is obtainable

EUI = 47 kWh/m2 pa

Annual heating costs around £775

Potential for reducing this to less than £200 pa with the addition of a 4kW pv array

CAVEAT

The results of the outline SAP calculations are based on reasonable assumptions but are subject to more detailed surveys. The calculations are displayed for information purposes ony and as an indication of what may be achievable.

4.6 Suggestions for further discussion

The NT has an onerous task ahead to achieve its ambitions for reducing the carbon footprint of its properties.

Streamlining the process of decarbonising such a diverse number of buildings will be difficult but there are techniques which will provide economies: in the surveying of the buildings, and the concept design.

It is hoped that the contents of this report will provide food for thought and a possible direction for the retrofitting of this, and possibly other historic rural buildings.