Energy-efficient renovations

When a house is renovated, it is wise to improve its energy efficiency at the same time (roof, external walls, foundations and floor). Adding energy efficiency is the only aspect of renovation that will pay itself back with interest. 

When designing a new building or renovating an existing house, it is wise to be well-prepared for coming future energy efficiency requirements. As each house is unique, each energy renovation project must be carefully planned according to the specific needs of the house.

Notable potential

From the energy conservation point of view, renovation of existing building stock represents by far the largest potential in the building sector. However, at the same time, from the technical point of view, it represents the most demanding challenge. It is not feasible to bring the energy efficiency of an existing building up to date to the level of a passive building in a “normal” way. In most cases, it would not make economic sense.

Component approach

Instead of renovating an existing building in a single operation, a so-called energy optimised renovation is recommended. The economics of the process are optimised by looking at the repair of the building as a sequence of component-based projects throughout the life of the building. Each component – for example, the facade, windows, roof or the HVAC system – are upgraded or replaced at an optimum point after the service life has come to an end. Each time a component undergoes renovation, the best available technology is used to bring the energy efficiency to the passive level.

The energy efficiency of a building is more than just the sum of its components. Components interact and therefore it is vital to look at the building as a whole. Let us take an example. Old windows equipped with air inlets in the frames are replaced with modern, highly energy-efficient windows which do not have any air inlets. Fresh air is taken in through the heat recovery unit, and the HVAC system has to be modified correspondingly. This illustrates that a change of a component might have an impact on another component. Therefore, careful planning is necessary in order to avoid mistakes.

Through the years of several component-based renovation schemes, the energy efficiency of an existing building is upgraded in an economically feasible way to the passive level. At the same time, the life span of the building is extended in a sustainable way.

Source: Pekka Haikonen, Development Manager, Paroc Oy Ab, 11 March 2008.