The heat is on
Published: 17 June, 2014
Heating and ventilating covered shopping centres is a major cost for owners. But new technology is helping to bring costs down.
Heating and cooling shopping centres effectively will pay dividends both in saving energy and reducing costs, and with older M&E equipment inefficient by design and coming to the end of its lifespan in many centres, investment is inevitable whether installing new or retrofitting. But it doesn’t have to be as expensive as you might think.
“Malls are no longer sterile transient zones between the extremes of outside climatic conditions and closely controlled ambient conditions in shops,” says Chris Plummer, managing director at Hilson Moran. “They are filled with restaurants, retail kiosks, exhibition spaces, fashion shows and other such attractions designed to generate income and encourage shoppers to make their visit a fun packed family day out. Provision of an internal environment supportive of these diverse uses is essential.”
And balanced with this, Plummer says, is the need to minimise the extent of new plant and the increases in capital cost, space requirements and maintenance associated with it. Energy consumption must be minimised to keep service charges low and respond proactively to ever decreasing carbon emission targets demanded by progressively tightening legislation. And that is without considering the customers, who are increasingly aware of green issues and the wasteful use of natural resources.
“The biggest challenge in effective heating and cooling of the current shopping centre stock is that by their very design they are inefficient,” explains Mark Stott, head of technical consultancy services at Savills. “Most centres incorporate large open areas with great expanses of glass giving heat gains in summer and losses in winter, add in the constant influx of hot and cold air from the doors and you can see the design, size and structure of the centres mean that heating and ventilation systems are often inefficient and working overtime.”
Stott says the recent trend has been to move away from centralised heating and cooling systems, especially given that many systems are coming to the end of their economic lifecycle, and to encourage tenants to provide their own air conditioned environments to keep the shoppers comfortable.
“Buildings are responsible for 50 per cent of the UK’s carbon emissions, and shopping centres – which tend not to be energy efficient – account for approximately a fifth of the non-residential sector energy use,” he says. “Centres and their retail tenants traditionally have separate energy systems, often carrying out similar functions resulting in inefficiencies in running costs.”
According to Neil Lewis, managing director at Waterman Building Services, while shopping centres’ are capable of significantly reducing their overall carbon footprints with proper management of heating and ventilation systems, they have proved notoriously difficult in achieving carbon savings in practice compared to what should be achievable on paper. And analysis shows that this is not an engineering issue but more a commercial conundrum brought about by the differing drivers of the landlord compared to the tenants, and the diversity of size and complexities of those tenants.
“A shopping centre is 80 per cent tenant space and 20 per cent landlord space and it is understandable that to make the centre commercially viable to the landlord, the units are offered as serviced shells,” says Lewis. “Each tenant installs their own stand-alone services, usually with refrigerant heat poured out into the atmosphere but nothing is done to recover and reuse this heat back into areas such as the malls or food courts.”
Lewis explains how this wasted heat can be harnessed in the common areas of the centre. A condenser water circuit can be installed fairly simply around the building with each unit rejecting heat from comfort cooling into this energy “dump” from where it can be used for a multitude of purposes including heating the malls, hot water provision for public toilets and can even be exported to commercial or residential buildings either on site or near the centre.
But with installations of this kind financed through the service charge, Lewis warns that there may be reluctance from tenants to accept an increase in the cost of occupation at what is still a difficult trading period.
“If the energy is recovered, what fair pay backs can be offered to the tenants who have also had to invest more capital up front to incorporate the system into their installations?,” he asks. “Large anchor tenants will be keen to embrace these initiatives for corporate responsibility. Not so the fledgling start up business taking a small unit and needing to reinvest all profit back into making the business viable.”
As with any upgrades to M&E equipment, often the most efficient way of replacing or retrofitting is to do the works in conjunction with a major refurbishment, allowing architects and engineers to reflect on how plant has performed and upgrade them to respond to the needs of modern retailers and customers, according to Plummer.
But heating and cooling shopping centres doesn’t have to involve the use of new plant at all with more and more being done to design out expensive M&E equipment.
“Good shopping centre refurbishments will initially aim to reduce reliance on expensive mechanical plant and the consequent energy consumption by passive means; designing out excess heat gains by careful roof design and material selection while making the best use of natural daylight as well as using the latest advances in lighting technology to reduce power consumption and unwanted heat gains,” explains Plummer.
And small logical steps can make a big difference: “As plant and equipment comes to the end of it economic lifecycle, consideration should be given to each system and the building as a whole as changing or upgrading any singular system can have an impact on the performance of the building,” says Stott.
“Changing the lights over to LED for example can impact on the heat load of the building and the performance of the heating system, and replacing windows or doors can have similar impact on both the heating and cooling.”
Potential strategies for mall ventilation include natural and mechanical ventilation and mixed mode systems whereby use is made of outside air to provide cooling mid-season, instead of resorting to expensive mechanical cooling.
“Don’t forget that the cheapest heating, cooling and ventilation can be free and some shopping centre owners have decommissioned chillers and not needed to turn them back on,” says Matthew Tippett, head of sustainability at JLL property & asset management who recommends BCSC’s guidance note 68 on natural ventilation design. “For new build and bigger refurbishments, natural ventilation and mixed-mode with mechanical systems should be explored. Not only can this save money, it can also create a more natural environment for shoppers.”
Given the large roof areas of many centres, Solar PV systems are also a growing area of investment. And according to Plummer, deciding on the best strategy is aided by the use of Computational Fluid Dynamics (CFD) studies to predict the air movement and temperatures throughout the malls.
“Such design tools are, in the right hands, very powerful and can assist designers in achieving the optimum balance between capital expenditure, energy consumption, carbon emissions and operating costs while keeping shoppers happy and spending,” he says.
“I have also seen an increase in the number of new developments incorporating CHP systems,” adds Stott. “Energy savings from installing centre wide systems utilising CHP and tri-generation of heat, power and cooling can lead to significant overall reductions in both running costs and carbon emissions when applied to the overall energy consumption of a shopping centre.”
Air-curtains, which create an invisible curtain to prevent heating or cooling infiltrating or escaping tempered mall areas are another option, and according to Adam Fjaerem, technical sustainability and carbon manager at JLL property & asset management, manufacturers have become much smarter in their approach to designing and installing them.
“Using a combination of modelling software for air flows linked to improved controls and connectivity to the Building Management System, these curtains are much improved on the offerings of a decade ago,” he says.
The UK government is committed to delivering energy security while accelerating the transition to a low carbon economy with carbon dioxide emissions to be reduced by a minimum of 26 per cent by 2020 against a 1990 baseline. Stott says future plant replacement and new developments will see the use of greener more sustainable systems, with considerable emphasis on alternative systems beginning to be seen within the industry. Many new developments use mixed mode or passive cooling systems combining natural ventilation or a combination of natural and comfort cooling, which provide the benefits of both energy efficiency and improved comfort.
“Unusually, the technologies and concepts are all available, tried and tested and ready to go,” says Lewis. “What will realise these savings will be a mind shift in facilities management and funding options together with a continuing acceptance that energy reduction must take place if for no other reason than reducing expenditure to achieve a worthwhile profit.”
And Plummer concludes: “Innovative architecture, supported by well researched and rigorously tested engineering design has the ability to bring old shopping centres up to new standards at a lower cost than starting from scratch. That has to be good news for developers, retailers and the environment.”