Integration, integration, integration

Schools & colleges are increasingly seeking efficient whole building solutions for climate control. Heat recovery systems can be the answer

Educational facilities are typically areas of high energy consumption – with multiple requirements for lighting, internal climate control, hot water and refrigeration to ensure they create a comfortable and positive learning environment for young people. However, these systems often operate separately, which can mean a huge amount of energy is wasted.

Changes to part L of the building regulations, due in April, will have a wide impact on the education sector, as it demands a 9 percent increase in efficiency for non-domestic buildings, compared with the 2010 regulations. This, combined with a 33 percent rise in the cost of carbon ‘allowances’ for 2014-15 under the government’s CRC energy efficiency scheme (which affects all organisations in the UK except state-funded schools), provides an extra imperative for energy efficiency to be improved. Set against a context of rising energy prices, the case for reappraising whole-building energy strategies for efficiency savings is clearly growing.

Fully integrated climate control systems incorporating heat recovery can improve energy efficiencies. This is because heat recovery solutions can deliver high levels of comfort, while dramatically lowering running costs and carbon emissions in both new and refurbished buildings, driving savings on energy bills and surrendered carbon allowances. Heat recovery systems integrate heating, cooling, ventilation, air curtains and hot water, recovering “free” heat from areas requiring cooling and using it to heat others and to provide hot water to bathrooms and kitchens.

Daikin’s VRV heat recovery systems, for example, are suitable for any size of building. The “three-pipe” system is a far more efficient way to recover heat than a two-pipe system because, in the latter, gas and liquid refrigerant flow as a mixture, so the condensing temperature has to be higher in order for the system to function effectively. A three-pipe system’s dedicated gas, liquid and discharge pipes, on the other hand, mean heat can be recovered at a lower condensing temperature, which means less energy is used and the system is far more efficient.

The latest version of the system, VRV IV, is on average 28 percent more energy-efficient than its previous incarnation. It is based around the VRV IV heat pump, which has a larger heat exchanger than previous models, so it uses less power, and features three new innovations: variable refrigerant temperature technology, continuous heating during defrost and VRV configurator software.

Variable refrigerant temperature technology allows the system to respond to heating or cooling requirements by monitoring the required capacity and weather conditions. By continually adjusting refrigerant temperature to match heating or cooling demand and the outside temperature, less power is needed, efficiency is increased and comfort is improved. An added benefit is that higher refrigerant temperatures prevent cold draughts.

Each of the system’s eight modes can be selected at any time to suit individual building needs, depending on whether efficiency, comfort or reaction to load is the priority. Field trials of a VRV IV system operating in “eco” mode – varying refrigerant temperature continuously to maximise efficiency – demonstrated up to 60 percent less energy was used in cooling and 20 percent less in heating, compared with a previously installed VRV III system.

Continuous heating during defrost also improves comfort, avoiding a drop in indoor temperatures during the defrost cycle that can happen with other systems. The result is a system that runs more efficiently, keeping occupants comfortable all the time.

As well as efficiency, it is important to consider how flexible a whole building climate control system is to be able to cope with changes, such as to internal layout or classroom use. Modular systems such as VRV IV are ideal, as not only can they be scaled to fit the size of building, they can also be adapted to meet future demands.

For retrofit projects, installation flexibility is also a prime consideration. Not only can VRV systems be installed floor-by-floor to minimise disruption to staff and students, Daikin’s new branch selector boxes (which link the indoor units to the heat pump) are also light and compact, speeding up installation. They are also quieter, making them perfect for noise sensitive areas such as classrooms.

VRV configurator software simplifies commissioning, allowing remote configuration of settings, making it much less time-consuming to set up. Ongoing maintenance is easier, too, thanks to an intuitive graphical interface, allowing operational data and errors to be evaluated quickly and accurately.

Integrating heat recovery with other building systems using intelligent controls can improve overall efficiency and reduce energy use further. In fact, intelligent control of a heat recovery system is crucial, as this allows monitoring zone-by-zone within a building, ensuring that heating, cooling and ventilation levels are optimised to maximise comfort.

Intelligent controls, such as Daikin’s intelligent touch manager, use smart technology to provide daily data and future energy projections to deliver more energy-efficient climate control by allowing system operations to be adjusted in line with usage patterns. They can be used to integrate climate control seamlessly with other building management systems for easier commissioning and maintenance.

Interlocking climate control with other equipment saves energy and increases comfort. For example, interlocking climate control with presence sensors to detect room occupancy allows the automatic change of temperature settings or climate control to be switched off in unoccupied rooms. Systems can be interlocked with fire alarms, allowing them to perform an emergency shutdown of air conditioning and ventilation units in the event of a fire.

Intelligent controls allow a comprehensive history of the system to be viewed, to help facilities managers optimise settings and operational parameters to maximise energy savings, improve comfort and enable preventative maintenance. Some systems can also be accessed over the internet, enabling control of building systems remotely via a PC.

Additionally, energy consumption can be monitored across a range of equipment, including climate control, to pinpoint areas of a building where the most energy savings can be made. Daily and monthly data and energy consumption projections are then provided to monitor performance against targets and previous years.

Integrating heating, cooling, refrigeration, hot water provision and ventilation is an excellent way to dramatically improve energy efficiency, lower CO2 emissions and save on energy bills. For local education authorities, schools, colleges and universities looking to achieve the highest levels of efficiency, maintain high levels of comfort and (perhaps most importantly) create first-class learning environments, it is well worth considering a whole building solution with heat recovery.

The author of this article, Martin Passingham, is product manager, DX at Daikin UK W:


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