IMPACT is a specification and database for software developers to incorporate into their tools to enable consistent Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). IMPACT compliant tools work by allowing the user to attribute environmental and cost information to drawn or scheduled items in the BIM. Put simply, IMPACT takes quantity information from the BIM and multiplies this by environmental impact and/or cost ‘rates’ to produce an overall impact and cost for the whole (or a selected part) of the design. The results generated by IMPACT allow the user to:
- analyse the design to optimise cost and environmental impacts.
- compare whole-building results to a suitable benchmark to assess performance, which can be linked to building assessment schemes.
The overall aim of IMPACT is to integrate Life Cycle Assessment, Life Cycle Costing and Building Information Management.
The IMPACT process
IMPACT works with a wide range of building types from the earliest stage of design onward. Initially, the user selects a building template with predefined material information. As the design progresses the predefined material information is refined and expanded by selecting elemental constructions (e.g. complete roofs, external walls, windows) from a library of alternatives. During the detailed design stages the user increases accuracy further by replacing library constructions with building-specific component and material information.
Whole building assessment
IMPACT uses a whole-building assessment method involving the detailed measurement of each constituent product/material/component. When used in conjunction with operational energy and water consumption tools the interplay between the initial construction and operational impacts can be analysed to optimise the design.
This approach is in line with the European Committee for Standardisation CEN/TC 350 (sustainable assessment of buildings) conclusion that LCA and LCC should both be included in whole-building assessment. The benefit of whole building assessment is that the performance is based on comparing a whole building design to another whole building design, instead of, for example, comparing an external wall design to another external wall design (and then, separately, comparing roofs then windows etc.). Assessment at the building level means that only the building’s high-level function (such as office or residential) must be defined. The variable functions of the constituent elements may differ according to building-specific design requirements.
Multiple environmental issue assessment
With the view that only a wide spectrum of issues can approach a holistic view of sustainability, IMPACT is able to measure numerous indicators covering issues such as toxicity, water and resource efficiency in addition to carbon and climate change. Each indicator may be reported separately or a range of indicators can be combined into a single-value BRE Ecopoint result for simpler comparison.
In addition to detailed reporting of individual environmental indicators, IMPACT allows reporting to represent impacts over defined life-stages, as required by European Committee for Standardisation CEN/TC 350 for integrated assessment of sustainability.
“Cradle to grave” assessment with variable study periods
As buildings and other structures have long design-lives it is often the case that a significant proportion of the overall impact and cost will come from operation, maintenance and demolition. Typically, the majority of carbon emissions associated with buildings are due to the consumption of fuel/energy for heating, cooling and power. Similarly, water consumption and the maintenance and replacement of the building fabric have a considerable effect overall. However, as improvements in operational performance are achieved the relative importance of embodied impacts increases.
IMPACT is able to study the impact and cost of a design from between 0 (installation only) and 80 years allowing for the effect of different design and service lives to be exposed. When IMPACT is used in conjunction with operational energy and water consumption tools the interplay between the initial construction and operational impacts can be analysed to optimise the design.
Life-cycle costing (LCC)
The cost of operating and maintaining a building builds up over time and is significant when compared to the original capital cost of construction. Increasingly project teams are asked to undertake LCC to demonstrate cost-effective design and to plan expenditure over the building life. Equally the consumption of in-use resources has a significant effect on environmental performance so LCC can be used to justify low-impact design decisions.
IMPACT is aligned with latest BSI and RICS industry guidance on life cycle costing, and will provide early indicative estimates as well as more detailed estimates at later stages of design. It will also enable shorter periods of assessment than the entire life cycle (e.g. to match funding requirements).
IMPACT also allows life cycle costs to be reported over the different phases of the life cycle, as required by the European Committee for Standardisation CEN/TC 350 for integrated assessment of economic sustainability.
Environmental benchmarking for whole building assessment
A substantial benchmarking exercise has been undertaken as part of the IMPACT project to enable whole-building environmental assessment. For each building use type a sample of typical buildings (known as archetypes) are assessed and combined into a single benchmark representing average performance. The performance of a user’s building can then be compared to the benchmark in order to assess performance. This approach has been developed for integration with whole building assessment schemes like BREEAM.
It is anticipated that users who use IMPACT results as part of a BREEAM assessment will submit their BIM to BRE Global to contribute to the sample of buildings used to create the benchmarks. In this way, the base-line performance set by the benchmark will become progressively more challenging in line with overall market attainment.
Interoperability and IFC
The partners who developed IMPACT believed that open transmission and storing of information is a key enabler of Building Information Management (BIM). The use of the ISO open-source Industry Foundation Class (IFC) format in IMPACT ensures that openBIM is achieved – allowing sharing and collaboration across platforms and applications.
IFC integration into IMPACT is a key aim of the IMPACT project.