Space Heating - The heat is on01 February 2005

Heating large premises is a major challenge for employers seeking to ensure comfortable working conditions for employees, as well as the protection of the building's contents (such as stock or equipment) and fabric.

Long-term running costs can mount up, especially where there is an inefficient heating system in place. Whether old, in need of maintenance or just the wrong type of heating for the premises, an inefficient system is a drain on precious resources and carries a high operational price tag.

Yet the perception is that many users and owners of large premises have been slow to deal with such shortcomings, reacting instead to day-today demands and failing to put in place longer-term strategies.

"The Climate Change Levy was the first punitive attempt to make people more aware of the tax implications of not introducing better systems of space heating," says Simon Hartles, marketing director, Ambi-Rad Group. "However, there are many building owners that are still not implementing these changes; they are more concerned with the practicalities of the layout of the plant or issues arising within it."

There are other pressing reasons why those responsible for the heating of almost any large industrial or commercial space need to review their procedures. When the European Performance of Buildings Directive is enshrined in UK legislation at the end of 2005, many building owners, operators and energy managers will find the energy performance standards of their premises coming under ever closer scrutiny.

If the mechanism for building certification is policed well, buildings will be subject to continual inspection to verify the energy efficiency levels and greenhouse gas emissions of their heating and other equipment. The EPBD aims to align building standards across Europe, with a strong emphasis on reducing energy consumption. The tough new standards for new and refurbished buildings should cut fuel usage by one fifth by 2010. Carbon emissions would be reduced by 22%, helping the EU to meet its climate change commitments under the Kyoto Protocol.

As Hartles points out, if the far-reaching climate change ambitions of the directive are to be realised, it will require a substantial shift of approach and thinking about carbon emissions by the entire heating sector - manufacturers and users.

New and existing buildings will be considered separately. Energy performance standards will apply to all new buildings from January 2006. Larger existing premises of more than 1,000m2 will be subject to a full feasibility assessment of alternative heating and energy systems before construction works begin. Refurbishment or renovation projects will also have to upgrade overall energy performance to meet new national standards.

Any heating system of more than 20kW output and more than 15 years old, and all air conditioning systems over 12kW, must be regularly inspected. Boilers fired by non-renewable fuels will come under particular scrutiny.

There is a three-year period of grace following national implementation to allow EU member states to set up systems for issuing Energy Performance Certificates and equipment inspections. This presents an opportunity for many businesses that have neglected to address the demands of the directive to make the necessary investments in heating systems that are both compliant and cost effective.

"All the incentives to implement a workable, decentralised approach for heating large building spaces are there," adds Hartles, "from today's very high efficiency technology solutions to all the regulations that now have to be complied with."

There is another key incentive - the Enhanced Capital Allowances scheme introduced by the government, where up to 100% of capital outlay and installation costs on heating solutions can be reclaimed in the first 12 months. Hartles thinks the scheme is laudable, but says uptake is mainly seen on large projects where capital investment schemes have to go before the board.

"Most projects in this country are now relatively small, so you need to give people better incentives to switch to higher efficiency technology," he adds.

"Sustainable energy is important and right in the longer term, but there are plenty of pragmatic decisions that can be made now to reduce gas usage by 25 to 30%. Where existing boiler plant is very old and heating large premises, the savings can be up to 60%."

There is a wide range of industrial and commercial heating systems now on the market to meet that challenge. Basically, they fall into four main categories: radiant tube heating; indirect-fired warm air heating; direct-fired warm air heating; and air induction systems.

- Radiant tube heating works like the sun, warming people and solid objects in its path. Mounted overhead, the heaters produce a comfortable, all-round warmth that is concentrated where it is most needed, at the lowest 2m of the building. No energy is wasted heating the large volume of air. The resulting energy savings over conventional convective systems can be considerable. The system is highly efficient at the point of use. It warms up very rapidly and recovers heat to comfort temperatures quickly should the temperature drop - for example, when a loading bay door is opened. Efficiency is increased by zone control - heaters directly over unoccupied parts of the building can be switched off.
- Indirect-fired warm air systems are well suited to small and medium-size premises. The systems are up to 92% fuel efficient, reducing energy consumption and costs. Emission levels are very low, in line with the most stringent European standards. Gas is burned in a heat exchanger. Fresh or recirculated air passes over this, with the warmed air delivered either directly from the unit or through ducting. Indirect-fired systems answer a variety of heating and ventilation requirements. They may be used for heating only, heating and ventilation, heating and cooling, or to provide summer ventilation.
- Direct-fired warm air systems provide effective, cost-efficient heating and ventilation for large-volume buildings where even heat distribution, reduced running costs and improved air quality are required. Direct-fired heaters burn fuel in the air stream, warming it directly before discharging it within the building. The system can use up to 100% fresh air and up to 80% recirculated air, in adjustable proportions, to meet requirements for air quality improvement and economical running. In summer, the units can be used for 'free cooling' ventilation.

A key feature of direct-fired systems is their ability to produce positive pressure within a building by forcing air in at a slightly higher rate than it is escaping through natural ventilation. The technology is being applied at a new pre-production and warehouse facility at one of the UK's most important car plants, using Stokvis Energy Systems' Econo-Air units. The eight direct-fired, gas-fuelled heaters have been installed at high level within General Motors' 400,000ft2 building at Ellesmere Port by PMP Building Services.

"We had decided to opt for a different type of heating system for this project away from the norm, seeking ease of installation to help meet an incredibly fast programme," says Bob Sowter, managing director of PMP. "Normally for premises of this size, you would have had a large number of smaller heaters and economiser fans, but the installation time would have been considerably more."

- Air induction systems work on the basis that heated air is forced out of nozzles at high speed, creating a negative pressure around the nozzle and inducing the surrounding air and recirculating heat from the roof space - heat that would otherwise be wasted.

All of these systems are available from a number of vendors. However, anyone looking to invest in space heating technology should compare and contrast the many offerings available on the market.

There is, of course, another vital consideration when it comes to selecting the right equipment and that is the type of fuel that powers the solution. Ivan Thompson, managing director, Stokvis Energy Systems, says his company favours electricity "because whatever the environment you are heating, electricity is easily controlled by devices such as thermostats and time switches.

"Also, if you are heating space specifically for one person, but that person also needs to move around the building from time to time, you can introduce a movement detector so the heating is only activated when he is within that zone. It's simple, efficient and cost effective."

David Hillier, managing director, Bush Nelson, says that, with gas and oil, there are losses of efficiency, "largely because, when you burn energy, some of that is lost in the process and there is also a maintenance component to consider, as burners have to be cleaned, serviced and certified.

"Electricity is 100% efficient. For every pound sterling you spend, you get a pound's worth of usage. With gas, usage is about 85% and for oil around 60%, so you get what you pay for. With electricity, the losses are all taken at the power station - before it reaches the user."

Bob Towse, of the Heating and Ventilating Contractors' Association, sees gas and electricity as the frontrunners, but also points to other factors, such as the building regulations that now require the owners of premises to look to other energy sources. "Yes, you can use gas as your energy source, for example, but you may well have to provide 20% of your needs through renewable sources in future, such as solar power and photovoltaic cells.

"There is also a requirement for each energy source to be independently metered, so lighting would have to be measured separately from power supply, which will show up how efficient or inefficient a building really is."

The drive to ensure energy efficiency is being maximised, along with the increasing focus on the reduction of greenhouse gases, is pressing hard on industry, as it will increasingly on building designers when making decisions as to what form of energy supply solution should be used to heat those premises. The message is clear: an energy-efficient heating system could be a major contributor for businesses looking to make a big difference to their operational costs.

SOE

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