COST MODEL | OFFICE REFURBISHMENT data, security and management systems are becoming more common, but it has a capital-cost uplift. A decision to introduce hydraulic separation on a floor-by-floor basis is also a cost driver, but gives future flexibility and control. The IET Regulations require improved electrical protection on all designs after December 2018, which can result in an uplift for existing LV panels and local distribution boards. Refurbs now need to target Breeam Excellent as a minimum, and Well accreditation. One step further is the use of smart building design in which systems are connected and controlled via a single operating system. Cost model This cost model captures the engineering services costs of a medium refurbishment project within a central London location, and is based on a seven-storey building and basement level at 21,700m2 GIA and 17,320m2 NIA. It assumes the retention of all existing plant and services where feasible, with extended Cat A installations to suit revised office space layout, enhanced reception and new cycle shower facilities. The rates are current in the second quarter of 2020, based on a central London location. Main contractor OHP and preliminaries, professional fees and VAT are excluded. The building is designed to meet BCO 2019 and Breeam Excellent standards. Other considerations Where projects need to go ahead in phases while maintaining operational continuity, considerations which can add 2.20 to 5.70 per square foot GIA to the cost of services for refurbs include: Design of temporary works to facilitate repurposing of space or replacement of critical plant during occupation Introduction of multiple phases that require isolations, drain downs and temporary services modifications Out-of-hours working for tight programmes and to do work that is impossible during working hours Preparatory surveys to identify and ratify existing installations, to ensure critical services are maintained Establishing the condition of existing pipework to ensure reuse is feasible and there is no internal pitting and corrosion. Future considerations As electric vehicles become more commonplace, air quality will improve in London and building design will start to incorporate more mixed-mode ventilation strategies. As a consequence of Covid-19, a Building Council for Offices paper has recommended that short- and long-term changes are made to office design to ensure workspaces reduce the transmission of the virus. This is likely to affect the density of floorplates, a move away from hot desking, increased cycle parking, and strict limits on lift and meeting room use. HVAC systems will need to operate differently, including removal of thermal wheels and recirculation systems. Increased air supply and extract ventilation is likely, as is natural ventilation where practical. Bathroom design will probably move towards individual pods with hands-free flush, washing facilities and door operation. Even the method of construction will be affected, with offsite manufacture helping to mitigate the impact of onsite social distancing. CJ Category A fit-out works Unit Enabling works Strip-out and allowance to make good existing defective services m2 Space heating and air treatment Allowance for replacing perimeter heating grilles Allowance to clean chilled beams and rebalance mechanical systems; modify pipework zones to suit new tenancy splits Chemical flushing and treatment m2 Ventilation On-floor storeroom ventilation added m2 Electrical installations Reconfiguration and enhancement of exposed soffit lighting New and replacement lighting to suit reconfigured office plan Relamping of existing lighting m2 Protective installations Modification to existing sprinkler system to suit CAT A fit-out space m2 Rate 5.71 0.40 14.28 3.61 1.00 6.17 10.73 6.05 6.93 Builders work in connection with services 4.1% MEP subcontract prelims 15% MEP testing and commissioning 5% Category A fit-out total cost 87.80/m2 Notes: Assuming no occupation during the project. Extra over rate Shell and core works Unit Sanitaryware Sensor taps in lieu of push button, including power supplies Sensor flush plates in lieu of manual, including power supplies m2 Included in model above m2 10.00 to 15.00 Increase volume of air from 16L/s person to 20L/s per person from existing primary air handling plant GIA 3.00 to 5.00 UV lamps to AHUs (excluding lamp-replacement cost every 9,000 hours) m2 GIA 3.00 to 5.00 Electrical installations Antimicrobial UV lights to WC and refuse stores m2 GIA Space heating and air treatment Activated carbon filtration to air handling units Communications Air quality monitors installed in landlord core areas linked to BMS Full-body arch temperature scanner and associated EWIC Wall-mounted infrared laser temperature scanner and read-out screen Touchless intercom systems incorporating infrared beam to activate bell extra over Vertical transportation Lift-air purifiers Lift touchless app Lift touchless operating buttons (based on seven floors) Programming of doors to hold open when not in use, for improved ventilation m2 Nr 3.50 to 4.50 1.00 10,000.00 500.00 to 750.00 Nr 500.00 to 1,000.00 Nr per lift 2,000.00 1,000.00 3,000.00 500.00 m2 NIA 14.50 to 15.00 7.00 to 9.00 m2 2.00 to 2.50 Fitout works Space heating and air treatment Enhanced filtration to fan coil units activated carbon Enhanced filtration to fan coil units glass fibre H11 HEPA filters Communications Air-quality monitors installed across all occupied spaces linked to BMS Above are just a few examples of the more common type of approaches to dealing with Covid-19 and achieving Well standards, and are by no means an exhaustive list. There will no doubt be many refurbishment projects in the near and medium future that will need to ensure working environments adapt to the challenges that Covid-19 presents. It is vital engineering cost consultants are up to speed with how this can be achieved and the options available, and that they work with designers and clients to deliver solutions that are cost-effective and practical. 36 January 2021 www.cibsejournal.com CIBSE Jan21 pp34-36 Cost model.indd 36 18/12/2020 14:52