There are only two months to go until the 2019 CIBSE Technical Symposium gets under way at the University of Sheffield. The 9th CIBSE Technical Symposium, from 25-26 April, will be an opportunity to examine and share research, development and applications that will drive change in the regulation, creation and maintenance of the built environment. It will also present evidence of where there are still clear opportunities to benefit from established practices. Four papers on cooling are currently being reviewed by the symposium planning committee. They are:
‘Cooling with heat recovery for electrical cable tunnels in cities’ – Gareth Davies, London South Bank University
This paper explores how additional active cooling may be applied to reduce temperatures in tunnels running under cities, allowing higher electrical loadings to be used. With electrical power often distributed by underground cable tunnels, significant quantities of heat are often generated within them, increasing tunnel air temperatures. These are generally controlled using outside air introduced through ventilation shafts and circulated by fans to prevent overheating of the cables and to enable service/maintenance personnel to access the tunnels. The paper looks at a preliminary study, focusing on London, that investigates using a heat exchanger to extract heat from the outside air entering the ventilation shaft. The low temperature heat extracted can be upgraded using a heat pump to a temperature level that enables its use in a district heating system. Carbon and revenue cost savings are also discussed.
‘Overheating in residential developments: a comparative study highlighting how evaporative cooling can address this inefficiency’ – Laurence Cockman, Colt International
This looks at how a comparative study of identical developments gave the opportunity to assess evaporative cooling solutions to overheating. The study examines two blocks at the Kidbrooke Village Project that were identical in their orientation, layout and use, giving an opportunity to analyse, mitigate and advise on how to resolve overheating. The
blocks provide perfect conditions to monitor and compare the levels of internal temperature, relative humidity and external temperature over a 12-month period. An initial survey by Berkeley Homes attributed overheating to lighting gains and heat-loss transfer from the low temperature hot-water pipe network. Colt International designed a
solution to address this. One block had a Colt CoolShaft evaporative cooling system installed to provide pre-cooling of air supplied to the corridors, while the other had environmental fans for the supply and extraction of air to the corridors. This revealed a 4°C lower temperature in the former, demonstrating the economical, low energy use and high cooling capacity capability of the solution.
‘Assessing dehumidification in typical housing built to the Passivhaus standard in Jakarta, Indonesia – analysis for a hot, humid tropical season’ – Roy Sigalingging, University of Liverpool
This study was to determine whether energy-saving modifications to urban houses in Jakarta through the application of Passivhaus principles are an effective cooling strategy in a hot and humid climate.
With a hot and humid climate region, the air’s moisture level is high. Properly designed ventilation in a house will provide enough fresh air to keep the occupants healthy, remove odours and dilute indoor pollutants. However, ventilation in hot weather introduces more moisture into a house, which tends to raise rather than lower the indoor relative humidity. About 30–50% of the energy used for air conditioning for cooling is also lost through ventilation and air infiltration. The paper investigates the effects on indoor temperature and humidity on comfort and energy use by gradually improving insulation levels and airtightness to the Passivhaus standard in Jakarta row houses, to find the optimum setting for minimising cooling and dehumidification energy in air-conditioning. The goal was to achieve the lowest possible carbon emission building while maintaining a comfortable and healthy environment at an affordable cost.
‘Frese Delta T Control System perfecting return water temperatures in water-distribution systems’ – Stephen Hart, Frese Ltd Affiliate
The basis of this project was to discover the importance of achieving design temperature difference (ΔT), which is critical for system efficiency and for plantroom performance. During the investigation at the Technical University of Denmark in Kongens Lyngby, it was identified that although the district cooling system has a design ΔT of 6°C, many buildings were running with an actual ΔT of between 1°C and 3°C.
When the water flow through a terminal unit exceeds the design flow and the energy from the water cannot be efficiently transferred to the building, the power saturation point of the coil is exceeded, and the ΔT drops below the design value for that terminal unit. Overflowing the coil consumes extra pump energy and lowers the efficiency of chillers, boilers and renewable energy schemes. Coils perform most efficiently when the ΔT between the flow and return water to and from the coil is at the manufacturer’s design ΔT of the coil. In the study, when a selected coil was fitted with a Frese Delta T Control System, the pump energy consumed was 77% lower.
For more information about the Techncial Symposium and to book visit www.cibse.org/technialsymposium