Air Quality Assessment – Large Scale Mixed-Use Redevelopment, London

02.10.17

REC was commissioned to conduct an Air Quality Assessment in support of a planning application for the proposed redevelopment of Castlewood House and Medius House, located on New Oxford Street, Camden.

The proposals comprised the demolition of the existing Castlewood House building and construction of a replacement ten storey mixed use building, plus ground and two basement levels, including the provision of retail (Class A1 and/or A3) and office (Class B1) floor space. The proposed works at Medius House comprised external alterations including partial demolition, retention of the existing façade and two floor extension to provide 20 affordable housing units (Class C3). The proposals also included associated highway improvements, public realm, landscaping, vehicular and cycle parking, bin storage and other associated works.

The site is located within an Air Quality Management Area identified by the London Borough of Camden as experiencing elevated pollutant concentrations. The proposals therefore have the potential to introduce future site users into an existing area of poor air quality. Additionally, the development has the potential to cause air quality impacts at sensitive locations, such as fugitive dust emissions from construction works and road vehicle exhaust emissions from additional traffic travelling to and from the site. As such, an Air Quality Assessment was required to quantify pollutant levels across the site, consider its suitability for the proposed end-use and assess potential impacts as a result of the development.

Potential construction phase air quality impacts from fugitive dust emissions were assessed as a result of demolition, earthworks, construction and trackout activities. Suitable mitigation measures were recommended during the construction phase to reduce potential impacts to an acceptable level.

Dispersion modelling was undertaken in order to quantify pollutant concentrations at the site and assess the potential exposure of future site users as a result of road vehicle exhaust emissions. Pollutant concentrations were predicted across both Castlewood House and Medius House at the ground to eighth floor levels. The dispersion modelling predicted high pollutant levels at locations where residential units are proposed within Medius House. As such, appropriate mitigation was recommended for the affected units, including sealed façades, filtered mechanical ventilation and a high specification of window tightness. Pollutant concentrations at Castlewood House were also predicted to exceed the air quality standards and therefore sealed façades were also recommended to protect future users from elevated concentrations.

A screening assessment was undertaken to determine the potential for vehicle trips generated by the development to affect local air quality. This indicated that impacts were anticipated to be not significant.

The London Plan states that new developments must be considered Air Quality Neutral. Pollutant emissions associated with energy consumption within the development and traffic generated by the site were compared to relevant benchmarks. This indicated that combined transport and energy emissions from the proposals were below the combined benchmark and as such, the development can be considered to be Air Quality Neutral.

Based on the assessment results, the site was considered suitable for the proposed end-use subject to appropriate mitigation measures.

To find out more about our Air Quality Assessments, click here.

Air Quality Assessment - London