DATA CENTRES AND WATER HEATERS SPECIAL FEATURES This month: Hot-water use analysis; Luna project; data centre commissioning; AI in data centres; regulating humidity for servers IN HOT WATER Analysis of two hotels by Elementa Consulting revealed that actual hot-water use is around half of what systems are capable of supplying. Elementas David Glossop says this is resulting in much lower carbon savings in new services designs O ur industry has made significant steps towards reducing the energy consumed by the buildings we design; however, PAPER the contribution to this agenda ACCEPTED of water services storage and Technicalm distribution has yet to be fully grasped. Symposiu posium The Building Regulations and efficiency /sym w.cibse.org targets set by Breeam and Leed, for example, ww il 25-26 Apr plant that has been oversized to serve the theoretical peak load will not have led to significant drops in demand and 9 201 work efficiently when trying to modulate to satisfy lower demand. The outflow from sanitaryware and appliances. main water booster sets would also be oversized for the actual loads. Standards for storage and sizing criteria for To compare actual water use with theoretical calculations, consumption have not kept pace, however. Elementa Consulting did in-use tests at two hotels of differing styles For residential and hotel building types, the andoccupancies. National Calculation Methodology (NCM) templates predict high levels of domestic hotCentral London hotel water consumption a prediction shared with The first study was on a central London hotel with around 800 rooms Swedish and Danish calculation methods. and a well-used restaurant catering for guests and non-residents. It Systems designed to optimise operation using runs at a high level of occupancy, which was taken into account. The these assumptions increase loadings back measuring equipment monitored hot-water use and highlighted two onto the system that may not reflect actual main aspects hot-water consumption and timing of peak loads. demand profiles using water-saving fixtures. The sanitaryware is dated and does not make use of aerated fittings, Buildings with high domestic hot-water and there is a high proportion of baths versus showers. Current demands have been targets for the installation calculation assumptions would predict hot-water demands of 131,000 of combined heat and power (CHP) and litres per day; however, the hotel had an average use of just 60,000 litres other technologies to meet the base demand, per day. Traditional demand histograms have pronounced peaks in allowing higher run times and better the mornings and evenings, with a secondary peak at midday, but this paybacks. Where their design is based on the hotel had a much smoother loading in the mornings and evenings. It NCM, the assessed base load is unlikely to highlights the risks in applying a standard approach. If system recovery match reality, so anticipated paybacks and time is matched to this profile, the primary plant size can be reduced. carbon savings will not be realised. Bulk storage tanks, if oversized, present a Family hotel risk of poor turnover of water and stagnation, The second survey was of a family hotel with a restaurant open to leading to reduced water quality and the guests and non-residents, plus a spa and pool complex with separate risk of increased storage temperatures. With splash pool. The hotel is less than 20 years old and has not had any domestic hot water, large storage volumes lead major works since opening, and the survey was done during the school to increased storage losses. Heat-generation www.cibsejournal.com April 2019 45 CIBSE Apr19 pp45-46 Hot water hotels.indd 45 22/03/2019 16:57