How does it work?

The benefit categories most appropriate to assess for a scheme are selected through initial qualitative screening questions. This also enables a high-level indication of the potential range of benefits provided from limited input information.  Site-specific data is then entered for the chosen categories.

B£ST is based on robust research evidence and provides a structured approach to evaluating a wide range of benefits. Where feasible, it enables benefits to be quantified and monetised. Summary tables present results under the Ecosystem Services (ESS) framework and in terms of natural, social and other capitals. A series of graphs are automatically generated for use in reports. An Option Comparison Tool enables data from more than one assessment to be compared against baseline in terms of net present cost, benefit and value. B£ST enables a robust, standard approach to assessing the benefits of BGI that is consistent with broader (e.g. government) economic appraisal guidance.

Natural Greenspace in Surrey

B£ST was used to evaluate the benefits of establishing a SANG (Sustainable Alternative Natural Greenspace) to support new housing development. The site was Burpham Court Farm, a 32-acre site north of Guildford, leased and managed by Surrey Wildlife Trust. The establishment of a SANG would involve making the site accessible to the public. B£ST was used to evaluate the ecosystem service benefits of the SANG.

Roundhay Park, Leeds

Yorkshire Water undertook a study at Roundhay Park, in Leeds, to assess the potential of four options to reduce combined sewer overflow (CSO) and improve water quality. The costs, immediate benefits and wider benefits of SuDS and conventional drainage approaches were compared to the current drainage performance in the existing urban area.  Option 1 (storage of water in concrete tanks during storms) and option 2 (storage tanks and pipe upsizing) were conventional approaches.  Option 3 (combination of swales, detention basins, geocellular storage and connected pipes in public areas) and option 4 (same as 3 and also administered in private areas) were SuDS approaches. Option 1 was cheapest and reduced CSO spills but provided limited other benefits. Options 2, 3 and 4 offered similar underground sewer drainage performance. 3 and 4 both added a surface drainage benefit, and wider community and environmental benefits. Only option 3 generated a positive net present value (benefits greater than costs).

Glasgow

In 2013, Glasgow City conducted a restricted Environmental Impact Assessment to assess the costs, flood risk benefits and wider benefits provided by surface water management options, including SuDS. B£ST was used to assess the implementation of SuDS (e.g. green roofs, permeable paving, swales) with other surface water management measures that could form part of the city’s redevelopment plan. The proposed option was compared to a baseline ‘do nothing’ case. The benefit models assessed were amenity, carbon sequestration, enabling development, flood risk, health, recreation and water quality. The majority of the benefits provided by a SuDS approach were associated with flood risk reduction. Other notable benefits included recreation, water quality and amenity. The estimated benefits of the SuDS option were always greater than the costs (the benefit-cost ratio was 2.3 after confidence levels were applied).