Last edited 29 Aug 2016



[edit] Introduction

Retrofitting means 'providing something with a component or feature not fitted during manufacture or adding something that it did not have when first constructed' (Ref: Retrofit 2050: Critical challenges for urban transitions). It is often used in relation to the installation of new building systems, such as heating systems, but it might also refer to the fabric of a building, for example, retrofitting insulation or double glazing.

Retrofitting has come to prominence in recent years as part of the drive to make buildings more thermal efficient and sustainable. This can help cut carbon emissions, make it cheaper and easier to run buildings, and can contribute to overcoming poor ventilation and damp problems, therefore improving the health of occupants. It can also can increase building adaptability, durability and resiliency.

The Climate Change Act established a target for the UK to reduce its emissions by at least 80% from 1990 levels by 2050. Since 47% of the UK's carbon emissions are generated or influenced by the construction industry, and it is thought that around 2/3rds of the housing we will occupy in 2050 has already been built, retrofitting is vital.

The 2014 study New energy retrofit concept: 'renovation trains' for mass housing', by Ronald Rovers, estimated that 40 million houses in the EU would have to be retrofitted by 2020 if carbon emissions reductions were to stay on track. This, he argued, would require the adoption of mass retrofit techniques, some of which have been piloted in in the Netherlands.

[edit] Retrofit techniques

Retrofitting in this context should involve applying an integrated, whole-building process, however, there are a number of basic techniques that can be used for key elements of a building:

[edit] Retrofit in practice

The process of retrofitting involves the careful balancing of different elements and their effects on the overall performance of a building. A change in one part of a building can affect another, and sometimes this is only apparent after irreversible defects have occurred. For example:

  • Sealing buildings to improve their air-tightness can cause condensation problems.
  • Insulating a roof without also ventilating it can the cause decay of timber structure.
  • Internal wall insulation will remove the benefits of thermal mass which may have a detrimental effect on fuel usage.
  • External wall insulation will prevent the thermal store of heat from solar gain to be utilised within the building.
  • Poorly installed cavity wall insulation can create cold spots that then have damp problems that are extremely difficult to rectify.
  • Pre-existing problems can be covered up, and so more difficult to diagnose and rectify.

Some of the most common problems facing retrofit include: under-ventilation, condensation, air leakage, mould issues, rising damp, interstitial condensation, and overheating.

It is very important therefore that these and other risks are understood and managed in a way that is appropriate to each individual project. Standard solutions should not simply be rolled out without proper consideration, and it is vital that care is taken to ensure high quality installation. At each of the four retrofit processes – assessment, design, installation and operation – it is advisable to have 'retrofit watch points' to help avoid problems such as:

  • Poor management of trades.
  • Poor integration of trades.
  • The adoption of inappropriate solutions.

Once a building has been retrofitted, the process of post-occupancy evaluation is important in determining its overall success and ensuring that lessons are learned for future projects. This can be involve monitoring fuel use, occupant surveys, air permeability testing, and thermographic surveys and so on.

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