John Durbin, Engineering Department Manager at Daikin UK, examines the significant energy savings possible using integrated environmental control and heat recovery solutions and how a new conceptual tool can help specifiers and end users visualise those savings.
Improving the sustainability of the built environment needs to become much more than a hypothetical aspiration. Indeed, the Pathways to 2050 – Key Results Final Report, which was produced on behalf of the Department for Energy and Climate Change (DECC), recognises that over the next 40 years, the carbon emissions produced by the UK’s buildings will need to be reduced to at least 45% of the 2010 level.
At present, many of the UK’s buildings operate quite separate systems for heating, hot water production, air conditioning and refrigeration. This means that a huge proportion of the heat energy produced as a by-product of air conditioning and refrigeration systems simply goes to waste, rather than being captured and used elsewhere in the building. Given that the energy required for climate control is one of the major factors affecting sustainability, we need to start addressing this issue now.
Control systems
By integrating climate control systems in an innovative way, it is possible to create a much more holistic and sustainable energy cycle within a building. Such solutions could cut energy usage by up to 60%, making a massive difference to the sustainability of the built environment if applied comprehensively.
For example, according to the Carbon Trust, the retail sector alone is responsible for around 3% of total electrical energy consumption in the UK and some 21 million tonnes of CO2 emissions per year. It also estimates that heating and hot water production account for 60% of a retailer’s energy bills, with refrigeration also making a major contribution.
So if we take a major department store, where refrigeration is required for cafes, restaurants and kitchens, it is easy to see how the high proportion of waste heat generated by this function can be reused elsewhere in the building, such as over door air curtains or to provide hot water in wash rooms.
Integrated solutions
One of the most effective ways to implement an integrated solution is by harnessing the high efficiencies of heat recovery, as provided by Variable Refrigerant Volume (VRV) technology. VRV’s great advantage is that it varies the refrigerant volume within an air conditioning system to match precisely the requirements of a building at any moment. This means that the output adjusts continuously to ensure that each area maintains its set temperature, while saving both money and carbon emissions, because it only uses the minimum level of energy required.
These highly energy efficient solutions can be developed for a wide variety of settings – whether on a major scale for airports, shopping centres and stadia; for complex environments such as leisure centres, hotels and civic buildings or for community facilities like schools, shops and health centres.
This whole building approach is demonstrated through a new online tool recently introduced by Daikin UK called Daikin City. This interactive virtual city enables specifiers to compare energy savings that might be achieved through the use of differing VRV-based technologies in a variety of buildings, such as a bank, hotel, school, restaurant and retail outlets. Visitors can view, via their computer or an iPad app, the impact that different energy efficient options have on an energy calculator, which displays the potential energy savings that could be achieved as part of an overall solution.
In the hotel, for example, the energy calculator tool shows how it is possible to use VRV heat recovery in conjunction with a heat recovery air curtain and a heat pump hot water module to reduce energy consumption by around 35%, compared with a conventional system. By using this tool, architects, specifiers, surveyors and engineers can have a visual indication of the energy savings that are potentially possible by developing an integrated solution.
Other energy saving solutions include Daikin’s CVP refrigeration heat recovery. Again the online tool explains the principles of the technologies in a clear and visual manner, providing an indication of the energy saving potential of VRV technology. In the case of a convenience store with a CVP refrigeration heat recovery system, savings of 24% can be made on a standard system.
Heat recovery can also be used for ventilation. Heat recovered from stale and contaminated air extracted from a room can be transferred to the fresh incoming air, which is then injected into the room. The recovery of energy from the exhaust air therefore reduces the cooling/heating load on the air conditioning system, while offering all the health benefits of clean, odour and pollutant free air. By automatic bypass of the heat exchanger, the additional benefit of free cooling is possible, where needed, when outside temperatures are below indoor requirements.
Increase efficiency
As well as the need to increase energy efficiency, reducing energy consumption will also be vital in helping to achieve the 2050 targets. Integral to this is the need to improve the monitoring and control of systems. This means changing user behaviour and enhancing our collective understanding of how energy is managed within our buildings.
Intelligent control technologies can play a significant role in monitoring and maintaining heating, ventilating and air conditioning systems (the largest user of energy in the workplace). In fact, intelligent controls could increase a system’s efficiency by more than 30%.
The key to successful control, however, is the ability to deliver reduced usage while effortlessly maintaining optimum comfort levels. For example, if a control can switch off a climate control system when a room is unoccupied, or a window or door is left open, then energy wastage is reduced automatically. If the system uses passive infrared (PIR), it will also be able to detect both room or zone occupancy and activity levels – a particular advantage for hotel rooms, where usage can be adapted automatically when the occupant is not in the room, or sleeping.
For commercial offices, banks and retail stores, a good intelligent control solution should be able to set heating and cooling levels zone by zone, so public and staff areas can be maintained at preferred temperature levels, while air curtains at entrances are controlled separately, as are meeting rooms and IT server rooms, thus maximising the overall energy efficiency of the building.
At Daikin UK, we believe that the integration of intelligent controls and innovative solutions is vital to making the dramatic improvements now required in the energy efficiency of our buildings. When this benchmark becomes the standard of design in all buildings, this will make a significant contribution towards creating sustainable cities of the future.
However, in order to achieve these major reductions in energy usage and improvements in energy efficiency, it is vital that a whole building solution is designed from the outset. By examining the temperature requirements of the entire building to incorporate a total integrated climate control solution, not only will it be possible to make buildings more sustainable, it will also help cut energy bills.