Power at your fingertips
Part L of the Building Regulations places great emphasis on measuring and monitoring building energy use. At least 90% of annual energy consumption of each fuel should be assigned to various end-use categories, such as heating, cooling and lighting. For buildings with a total useful floor area of more than 1000m², automatic meter reading and data collection facilities should be present.
The logic is clear – if you know what energy is being used, you are far more likely to control it efficiently. Today’s building management control systems can play a central role in reducing energy use and cutting energy bills.
An excellent recent example of how a good building management system (BMS) can contribute to greater energy efficiency is the Birmingham Hippodrome which won the Energy Management Award in the recent Building Controls Industry Awards. The theatre is home to the famous Birmingham Royal Ballet, and the DanceXchange. It has an 1887 seat main auditorium, a 206 seat studio theatre alongside studios, conference and hospitality areas. The Hippodrome opened in 1899 and since then it has been a highly popular venue, hosting some of the largest shows including a recent visit by the Bolshoi Ballet.
In common with most leisure and arts venues, the Hippodrome has to be aware of its running costs. With energy bills for the main auditorium running at £35,000 a year, this was clearly an area with potential for savings. Michael Cassell, BMS Project Manager for ADT Fire and Security, says he and his team were called in to help tackle this challenge. He says: “Energy prices are going up, so the client was becoming increasingly aware of the cost of energy for the building.”
Working with ADT, the facilities team at the Hippodrome identified that considerable savings could be made by upgrading the heating and ventilation system. “The original system was fitted during the building refurbishment in the late 1990’s. We had a very good idea of the efficiencies of the pumps and fans, so we were able to work out the potential savings using that knowledge,” explains Cassell. “We decided to fit variable speed drives to the uncontrolled fans in the main auditorium, and to the heating and chilled water pumps.”
The existing heating and chilled water pumps operated on a duty/standby arrangement, with the duty pump running at full speed while the standby pump was idle. Cassell and his team identified that savings could be made by installing frequency inverters on the various heating and chilled water circulation pumps and on the main air handling unit’s (AHU) supply and extractor fans serving the theatre.
By running both the duty and standby pumps simultaneously at 65% of their normal speed, the pumps are running closer to optimum efficiency, giving a reduction of 35% on the electrical power consumption whilst still maintaining the required water flow rate.
The client and supplier team also identified that the AHU’s supply and extraction fans were operating at full speed during periods of partial occupancy, particularly during rehearsal. To improve energy consumption, frequency inverters were installed on the AHU’s motors together with air quality sensors. This means that the speed of the motors can be controlled in proportion to the air quality levels being measured. Not only does this improve energy efficiency, it also improves comfort for occupants. ADT designed, supplied and installed 29 heating ventilation and air conditioning (HVAC) frequency inverter drives, varying in size from 2.2 to 30kW.
Quite a challenge
Moving the equipment through the theatre wasn’t straightforward. “The auditorium is quite high, so that did pose something of a challenge,” says Cassell. “Also, as the theatre couldn’t be closed down for the changes, the ADT team had to work around the requirements of the client. It was an ongoing process over three months where we worked during the day as there were performances most evenings. We also had to work in certain time slots if there were matinee performances.”
As well as improving the equipment running efficiency, ADT also worked on upgrading the BMS to use Building Automation and Controls network (BACnet) software. BACnet is a standard designed by the American Society of Heating Refrigeration and Air conditioning Engineers (ASHRAE). It is used across Europe, the USA and parts of the Far East. By using BACnet, it is much easier to link HVAC, lighting, fire, security and other building elements with a single user interface. One of the advantages that BACnet offers is that building owners are not tied to a particular manufacturer’s products for their building services equipment, but can select according to their own requirements.
An additional advantage of upgrading the BMS at the Hippodrome is that it was subsequently easier to adjust drives from a single point. As Cassell explains: “By upgrading the BMS to support BACnet, we could use ABB inverter drives. Use of BACnet allowed us to gain greater control and monitoring of the building’s performance and energy use.” In fact, the BMS upgrade doesn’t just affect the inverter drives; it also provides tighter switching of lighting, cooling and other building services.
The cost for these improvements was around £60,000, but the Hippodrome received a loan from the Carbon Trust for that amount. In the past year since the changes, the Hippodrome’s energy use has dropped by 5,500,000kWh. This represents a financial saving of around £17,500 a year. The loan will be paid back in less than four years, which means the Hippodrome will benefit from the savings very soon.
It’s clear that better control of building services can have a great impact on energy use reduction – and make big savings for clients. Building management systems are now highly advanced, and perhaps this has caused some clients to shy away from using them more. However, as Michael Cassell points out, they are missing out if they aren’t using building controls to increase energy efficiency: “Clients don’t yet fully appreciate the power they have at their fingertips.”
To find out more about how building management systems can contribute to energy efficiency, come along to the free Training Academy at this year’s M&E Event at London Olympia on 10 and 11 October. To see more details and to register, go to www.buildingservicesevent.com