Protestors gluing themselves to the M25 are demanding that more be done to insulate Britian’s homes and the government is considering more initiatives in this direction

Surveyors acting for mortgage lenders are in a good position to see how well we are doing insulating our homes and adapting to greener forms of energy. Readers will probably be familiar now with Energy Performance Certificates [EPCs] which are required whenever a house or flat is sold or let. Perhaps less familiar will be the U-values which we surveyors use to calculate the heat losses through various parts of a building including walls, floors, roofs and windows and how we might use this information to help clients make an informed choice when bombarded with conflicting and contradictory advice about insulation, boilers and triple glazing. 

The EPC is a four-page document which sets out the energy efficiency of a property using a colour banded system of A to G, A (green) being the best insulated and G (red) being the worst. Similar colour banded systems are a familiar sight on domestic appliances such as fridges and cookers. It is usually illegal to sell or let a property without an EPC and it is also normally illegal to let any property if it is poorly insulated with an EPC of F or G. 

The government has pledged to increase the minimum EPC score to C for privately rented homes by 2030. Surveyors valuing for by-to-let applications currently will normally be unable to recommend a security with F or G banding and by 2030 all D, E, F and G banded properties could be unlettable and potentially un-mortgageable as well. Buy-to-let landlords owning older, poorly insulated, properties should be prepared for some big bills if they expect to still be letting in 2030.  

There are a few exceptions to the general requirement for an EPC to be obtained or for the necessary standard to be met prior to letting. If the property is listed as being of special architectural value or is in a conservation area it may be impossible to add wall insulation or double glazing. A rented room within a house will not require an EPC although a self-contained flat within a larger house that has its own front door will. 

Further legislation could be proposed in due course making it illegal to sell a property with a low EPC score following on from the existing rules for lettings, so vendors would have to invest in additional insulation measures before offering the property for sale. This would to have the advantage from the government’s point of view of not costing the Treasury anything whilst at the same time emphasising its green credentials. The cost and delay implications for agents and vendors putting properties on the market would be massive however.  

Within the surveying profession there remains some scepticism regarding the accuracy of EPCs.  Green Deal Assessment Mystery Shopping Research published by the Department of Energy and Climate Change in 2014 found that when five different EPC assessments were performed on the same 29 residential properties nearly two-thirds of them resulted in an EPC certificate that varied by at least two bands. This was a very small sample and not necessarily representative of the system as a whole and it was seven years ago however it is worrying that a property can be wrongly assessed with potentially serious implications for the property owner or landlord. 

There is also a risk that the inconsistency in the system leaves it open to abuse with the possibility of landlords or property occupiers persuading the EPC assessor to give them a better rating by tweaking the data. 

Surveyors know that much of the construction of any house is hidden and cannot be confirmed without exposure so that energy assessor has to make various assumptions about the property based upon its type and age. The level of insulation in roofs without access inside, and typically all flat roofs, can only be guessed at. We do not know for certain if a cavity wall has been insulated or what type of insulation material may have been used. 

When we surveyors deal with insulation issues we refer to U-values. U-values measure the thermal transmittance and how effective a material is as an insulator. We will be hearing more about U-values in the years ahead. Thermal transmittance is the rate of heat transfer in Watts through a material divided by the difference in temperature across that structure. Surveyors are familiar with the calculations (W/m2K} but you do not need the technicalities to understand that the lower the U-value the better insulated (and therefore potentially warmer) the structure will be. 

Workmanship during installation can strongly affect thermal transmittance so if insulation is badly fitted with gaps and cold bridges (a not uncommon situation in my experience) heat loss can be much higher. Thermal transmittance takes into account heat loss due to condensation, convection and radiation. 

A typical basic insulated cavity wall has a U-value of about 0.3. A less well insulated wall with a U-value of 0.6 will lose heat at twice the rate so the lower the U-value the better. For new construction the Building Regulations Part L set out to U-value requirements for new construction ranging down to 0.18 for external walls and roofs. If we are to insulate the existing building stock to the same standards as the Building Regulations require for new-builds (U-values down from 0.6 to 0.18) some fairly radical and very expensive building work will be required. 

When insulating our old housing stock it will not be enough to draught-proof, lag the loft and install double glazing. If the walls are solid without a cavity the walls will need to be lined either inside or out with thick cladding to achieve the required U-value. External cladding will completely change the look of the house. Internal lining involves major disruption to woodwork, plasterwork and decorations. 

Surveyors continue to offer helpful and constructive advice based on their clients’ circumstances and budgets and we are already warning about the potential implications for the buy-to-let market. We wait to see what further initiatives the government proposes. 

Peter Glover is a surveyor and author of ‘Building Surveys’ and ‘Buying a House or Flat’