- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 15 Jan 2015
Additionality of built developments
The concept of ‘additionality’ is used to identify the net (rather than gross) impacts resulting from an activity or project, that is, ‘...the extent to which something happens as a result of an intervention that would not have occurred in the absence of the intervention’ (ref English Partnerships Additionally Guide: A standard approach to assessing the additional impact of interventions). It is sometimes taken only to relate to positive impacts, however, this assumption would pre-judge the outcome of an assessment as most projects will have both positive and negative impacts.
Additionality is often used in the context of regeneration, regional development, local economic growth and housing interventions, adopted as an assessment tool for large-scale projects by the government. However, it can also be used to assess applications for funding, for individual programmes or projects, or for specific impacts such as greenhouse gas emissions.
Additionality can be used as a decision making tool, helping test and compare options and to assess where changes may be necessary. Assessments can be carried out throughout the development of a project, however, the greatest opportunities for change resulting from an assessment will come earlier rather than later.
Assessments may consider impacts such as:
- The quantity of outputs in an area.
- The consequences of impacts happening sooner than they would otherwise have done.
- Quality impacts.
- The benefits for target groups.
Impacts can be assessed from the top down, looking at general indicators of the impact of an overall intervention, such as local employment, or bottom up, assessing the impacts of specific actions. It may be appropriate to use both techniques to gain a clear understanding of the impacts of an intervention.
Assessments need to consider options in relation to what would have happened in the absence of the intervention (the reference case). This is not simply a matter of comparing options with the current position, as that position might change if the intervention were not to take place. For example, it may not be possible to simply do nothing, and alternative interventions may occur in the absence of the proposals. It is also necessary to consider external impacts that may be caused by the intervention but are not directly part of the project, for example, investment in an area may encourage further investment by third parties. Conversely, providing a new service may result in cost or price changes, may impact on existing services, or prevent alternative providers from offering the service.
This can create a very complex picture, and simplification may be necessary. The extent and detail of the assessment should be proportionate to the scale and likely consequences of the intervention.
Assessment can be used to help maximise impacts, whilst ensuring that the minimum resources are used to bring about those impacts. Where the impacts would not have happened at all without the project, it can be considered 'fully additional'. Where excessive resources are consumed to deliver the impacts this is referred to as ‘deadweight’.
 Related articles on Designing Buildings Wiki
 External references
Featured articles and news
The Chartered Quality Institute explain the pathway to success for organisations implementing management systems.
An introductory article looking at where a duty of care can arise in the construction industry.
House of Lords committee encourages the use of off-site manufacturing in new report.
Computational fluid dynamics (CFD) can go some way to show the impact of new buildings on their surroundings.
The shortlist for the 2018 prize for the UK's best new building is revealed.
Amendment to Bill aims to provide councils with greater powers to increase tax premiums on empty homes.
As the latest summer blockbuster 'Skyscraper' is released, we look at some of the best uses of buildings in film.
Read our introductory article on how to layout a building.
New cross-party report calls for combustible cladding ban to be extended to all high-rise residential buildings.
Dr Nicholas Falk, director of the URBED Trust, explains why metro cities are the future of urbanisation.