Creating low energy environments

In the UK, controlled environments often have to be housed in old, pre-existing buildings, which makes achieving energy efficiencies and reducing the carbon footprint a challenge. Susan Birks reports on Cavendish Engineers’ recent London seminar that showed that even in old buildings, low energy cleanrooms can be achieved.

Much of the building stock in the UK is old; this means that many controlled environment contracts involve putting new facilities into old buildings and, consequently, upgrading the existing facilities. These controlled environments are often “mission critical”, which means that the facility’s daily work programme may not be interrupted, and they have tight tolerance levels for humidity, temperature and cleanliness. The challenge is to ensure that the upgraded facilities meet the latest requirements for energy efficiency and reduced carbon footprints.

Specialist contractor Cavendish Engineers hosted a recent one-day seminar in London that addressed this challenge. The event consisted of six presentations covering the planning of a controlled environment project and what low energy technology to consider – ranging from modern chiller applications to new humidity controls and energy efficient lighting. Case studies were presented from a range of sectors, including the space industry and electronics, and there were a number of presentations specifically focused on energy efficiency in data centres.

Steve Allen, Managing Director, Cavendish Engineers, opened the event with an overall view of how to plan a low energy cleanroom project. He suggested that any energy efficiency project should start with a review of the new BSI (ISO) 50001 standard. Developed by energy management experts from more than 60 countries around the world, this international standard looks at the latest best practice in energy management. “Use this as a principle and you will achieve what you want to get in terms of energy efficiency,” said Allen.

Any energy efficiency project should start with a review of the new BSI (ISO) 50001 standard. Use this as a principle and you will achieve what you want to get in terms of energy efficiency

ISO 50001 will enable organisations to understand their baseline energy usage in order to decrease this amount and to reduce their carbon footprint. This is important at a time when governments are introducing financial penalties for those that don’t show improved energy efficiency. For example, this year and for future years, the rateable system on commercial buildings in the UK will be linked to an energy rating and companies will be charged if they are not below 100 kWhr/m2/year. Table 1 shows the steady reduction in UK energy benchmarks that has taken place over the past decade.

Cavendish is well placed to achieve such targets, having recently helped in a project to improve the energy rating of No. 9 Millbank, London – the HQ of ofgem (the consumer protection body that overseas the activities of the Gas and Electricity Markets in the UK). In 2008, its building had a rating in the region of G177. As a result of working with Cavendish, today it is down to D82.

To achieve such results, Allen suggests the first issue to tackle is Benchmarking: “If you can’t measure it, you can’t manage it!” He then suggested a review of the building’s “envelope” for heat loss, usually measured as the U value (rate of heat loss in W/m²/°C temperature difference across that element). Once the data is to hand, discussion can get underway with stakeholders – and not only those paying for it – to see what improvements can be made.

Next on the list is ensuring the building’s HVAC system is the most efficient. Many new low energy systems now exist on the market and Allen’s advice was that investment in higher capital expenditure technology invariably pays for itself very quickly in lower operating costs these days: “High capex usually means lower opex,” he said.

Investment in higher capital expenditure technology invariably pays for itself very quickly in lower operating costs these days

A useful project planning tool used by Cavendish is Building Information Modelling, ie. computer packages that provide a 3D model of the project that can be worked on by several engineers at the same time. “They offer great visibility of what you are building,” he said, enabling spacial and design issues to be dealt with early.

The next important step is to plan for energy measuring and reporting after the build. Too few companies follow this through, he said, and he recommends the type of reporting system that displays performance in the company reception area, keeping performance visible. Input power needs to be managed, he stressed, and at this stage it is important to set operation efficiency targets for the maintenance team.

Other useful advice for those planning projects was to push for off-site engineering where possible. “Use pre-engineered packages from specialists, as the shorter site time lowers the costs,” he suggested.

Use “proven technology” was further advice and he listed several new beneficial technologies worth considering: LED lights; Delta Conversion UPS (allowing low loads to be tracked with no loss of efficiency); Hydronics (such as variable speed drive pumps and Turbocor chillers); low energy humidity systems and voltage optimisation equipment.

The case study presented was the upgrade of the Class 8 facility used by UK spacecraft manufacturer. The leading European space company wanted lower operating expenditure and a better quality working environment from its 1952 building, which covered an area of 1,400m² and stands 5m high. Table 2 shows the existing energy efficiencies of the building and the targets the upgrade aimed to achieve.

Cavendish worked with the company to improve the envelope U-value using new insulation; LED arrays provided better lighting of around 1,000 lux; for the HVAC they looked at Specific Fan Power; EER control sensing technology was employed; and new flooring was also provided. The energy efficiencies were then remeasured to ensure the targets had been met.

Chiller technology

Frequently, the equipment consuming most energy in cleanroom facilities are the chillers. Stuart Kay, southern sales manager, for Airedale International Air Conditioning, looked at advances in chiller technology. Chiller suppliers, he said, have seen a switch in recent years from traditional chillers to low energy models.

Kay looked at the pros and cons of different types of compressors and technologies – screw, scroll, centrifugal, Turbocor and evaporator design – on the market. He also provided an energy comparison of the three main types (screw, scroll and Turbocor centrifugal designs) carried out by his company. This showed that the screw and scroll chillers were relatively comparable in terms of energy efficiency ratio (EER) and European seasonal energy efficiency ratio (ESEER), but that of the Turbocor design was significantly better.

Chiller suppliers have seen a switch in recent years from traditional chillers to low energy models

He also looked at new low energy technologies such as electronic expansion valves; microchannel (MCHX) drivers, a technology developed by the motor industry which lowers refrigerant charge; and use of Electronically Commutated (EC) fans.

Kay also explained the benefits of “Free Cooling” – a method of harnessing low external air temperatures to assist with chilling water.

When the ambient air temperature drops to a set temperature, a modulating valve allows all or part of the chilled water to by-pass an existing chiller and run through the free cooling system, which consumes less power and uses the lower ambient air temperature to cool the water in the system. Over a year (cumulative hours, London, UK) this can save more than 50% of the energy consumed by a conventional chiller, thus greatly reducing operational costs.

Brian Glynn, operations manager, LSii Europe, looked at the rapid development of LED lighting over the past decade, which now offers many benefits. Those he listed were energy efficiency; long life span; low maintenance; robust and flexible designs; recyclability (some suppliers will collect for recycling); and excellent colour rendering.

The LED driver technology – the main influence on the system’s life – has improved, and users no longer have to wait in semi-darkness for the LED array to warm up

He said the biggest advantage of LEDs is the improvement in the quality of the light generated. When high powered LEDs were introduced in 2006, they provided around 10 lumens per Watt – today a good quality LED will produce > 200 lumens. Another key factor is the colour rendering index (CRI), a measure of the ability of a light source to reproduce colours. Natural daylight has a CRI of 100, whereas a metal halide has 65. Good quality LEDs can achieve CRIs as high as 95, providing accurate colour rendering. The LED driver technology – the main influence on the system’s life – has also improved, and users no longer have to wait in semi-darkness for the LED array to warm up. The aluminium housings also act as a heat sink, so they don’t exceed body temperature (37°C).

New technology – linear dimming – is also being developed that will allow everything to be dimmed by a certain percentage, limiting the energy use accordingly, he said.

With a view to cutting energy in data centres, Kevin Ricketts, Schneider Electric, looked at the use of virtualisation tools to design energy efficient data centres. Colin Richardson, managing director of consulting company on365, looked at power and cooling in data centres and Gareth French, director, Humideco, looked at humidity control in data centres as well as other cleanroom environments.

Whatever the age of the building, considered implementation of the right technologies can help to measure and control energy use in such facilities.