NDOOR AIR QUALITY | DELOITTE LONDON HQ Air apparent Health and wellbeing was of utmost importance in the development of Deloittes new UK HQ. Achieving both Well Certified Gold and Breeam Outstanding ratings, Hoare Leas Sam Carlsson explains how a performance-based target was key to getting the design team engaged with IAQ on the project T he health and economic impacts of poor air quality within urban areas and inside buildings is becoming increasingly apparent, and mitigation measures are currently a key focus area for policymakers and those involved in designing the built environment. One New Street Square is Deloittes 25,800m2 UK headquarters, a workplace for 5,500 staff and providing facilities for their 13,000 strong London campus. The brief was simple: design this landmark HQ to lead the way in providing an environmentally sustainable and human-centred workplace, where the health and wellbeing of the staff isparamount. The fit-out was completed in 2018 and was the first in the world to achieve both Breeam Outstanding and Well Certified Gold ratings. It is also the largest Well Certified Gold commercial interior globally to date. With a human-centric approach to design and performance-based targets set by the Well Building Standard, delivering a building with exemplar levels of air quality was a core principle of the design, from the brief through to operation. Suggested indoor air quality (IAQ) parameters are defined in various industry guidance. See Air quality parameters box below for the parameters required by the Well Building Standard (v1)1 that were adopted in this project. To achieve these levels, detailed design, construction and performance measures were undertaken at each stage of design and construction. Measures During the early stages of design, a comparison of ASHRAE 62.1 (2013) outdoor air supply standards (used as part of the Well guidance) with UK benchmarks was undertaken. This found that, compared with Well guidance, much higher ventilation rates are expected in UK Building Regulations and industry guidance, such as that from the British Council for Offices (BCO) and CIBSE (see Figure 1). In terms of air filtration, Well recommends filtration levels of MERV 13 to filter outdoor air, equivalent to ISO ePM2.5 >65% (previously F7 filter), which are typical for commercial projects in London. Understanding that outdoor air quality varies with location, the latest version of Well (v2) has AIR QUALITY PARAMETERS introduced a tiered system based on measured outdoor air quality data. The annual average outdoor Formaldehyde levels <27ppb Total volatile organic compounds (tVOC) <500g.m-3 PM2.5 level on Farringdon Street, near the One -3 Carbon monoxide <9ppm . New Street Square building, is 16g m , which is PM2.5 <15g.m-3 below the Well v2 tier threshold for MERV 13 filters. PM10 <50g.m-3 However, filtration still needs to account for pollution Ozone <51ppb events, so balancing filtration levels with energy Radon 0.148 Bq.L-1 consumption is key. 8 June 2019 www.cibsejournal.com CIBSE Jun19 pp08-10 Hoare lea Deloitte Supp.indd 8 24/05/2019 14:14