BREEAM comes to the southern hemisphere
On a recent building-controls training assignment in the Republic of Mauritius in the Indian Ocean, Mike Malina found out how the building energy management system plays a key role in the effective operation of the iconic headquarters of the Mauritius Commercial Bank.
A first for Africa and the Indian Ocean area is the prestige building built to house the headquarters of the Mauritius Commercial Bank and built on sound principals of sustainable design, achieving both the Australian sustainability label ‘Green Star’ and a good BREEAM rating. It is the first building in the southern hemisphere to achieve a BREEAM rating. A fundamental part of achieving its energy and sustainability credentials has been the integrated building energy management system.
The Mauritius Commercial Bank headquarters building is located nine miles south of the capital of Mauritius, Port Louis, in an area near to the Ebene Cyber City which is fast becoming the technology and new information technology hub. It gives a commercial link between the African and Asian markets, enabling the Republic of Mauritius to continue to be a great economic success, in spite of problems elsewhere in the world.
This iconic 10-storey, 40 m-high, 10 000 m² building has a unique curved steel-framed structure forming an elliptical shape, like a large eye looking over this vibrant multicultural, historic tropical island. The building is surrounded by a 6 acre landscaped area maximising the natural resources of Sun, wind and rain in a tropical climate with an average temperature of 23.5°C, dry winters and very wet summers.
|Inside the headquarters of the Mauritius Commercial Bank. Maximum use is made of natural light.|
This climate presents a number of challenges very different to what many of us are used to in the UK. For instance, heating for buildings is not really an issue. The challenge is very much more of how to provide cooling in as energy efficient a manner as possible, minimising the impact on natural resources and the wider environment.
The orientation of the building starts with the fundamental design, which is to position the building with façades facing due north and south with substantial overhangs, practically eliminating all the direct solar gains. Energy consumption is also minimised by making use of free environmental cooling where possible and the use of a 400 kW 980 m² photo-voltaic array situated at ground level facing due north (as this is the southern hemisphere).
Rainwater is collected, harvested and stored in below-ground tanks, Fresh air is provided using a floor displacement ventilation system. All this is designed to provide a building that accommodates 750 staff of the Mauritius Commercial Bank, comprising open plan offices, two auditoriums seating nearly 300 people between them and also providing a large canteen facility and additional spaces. At full capacity, the building can accommodate 1100 people.
This combination of design and technology has enabled the building to gain the first BREEAM rating awarded in the southern hemisphere, by utilising this combination of building orientation, shading, renewable energy and rainwater collection for re-use.
Fundamental to the success and operation of a good indoor climate has been the integration of the building services with the architectural elements of the building design. At the heart of this is the building energy management system. This has been provided, installed and commissioned by Harnessing Environmental Technologies Ltd (HET Ltd) a Mauritian based solution partner for Siemens Building Technologies.
The aim was to achieve a fully intelligent and integrated building energy management system (IBEMS).
The building’s electrical and mechanical plant and equipment is controlled by the a Siemens building and energy-management system, which is currently being upgraded as part of a continuous commissioning process to the Desigo v5 platform, which provides even more powerful tools for energy monitoring.
The BEMS was implemented to provide efficient monitoring of the plant and utility supplies while maintaining a comfortable environment for the building’s occupants. The system provides control and monitoring for a range of building engineering services, as detailed in the panel.
Fine tuning and the continuous commissioning is being planned to use more intelligent control and systems integration, looking at ways to add more building services to be fully integrated on the BEMS and using more interfaces in a way to develop the BEMS. More sophisticated BEMS algorithms are being developed with Siemens to improve the ventilation and air conditioning of the building. One example is following the path of the Sun to adjust the indoor climate to achieve the optimum efficiency for the building zones, with the BEMS adjusting set points to gain even more efficiency, coupled with the optimum indoor climate control.
Energy-resources planning is also being taken into consideration in the BEMS for better use and control of water (grey and potable water) and electrical energy (electricity from the Mauritius Central Electricity Board and the on-site solarPV farm).
|One of the uses for electricity from this 400 kW solarPV array is to charge a thermal energy storage system for cooling the building.|
One final point is the energy contribution provided from biomass on the island; it is derived from ‘bagasse’, the fibrous waste produced from the island’s dominant sugar industry. 16% of the power demand of Mauritius is provided from this source, with a further 5% is provided by hydro-electric power. The remainder, and still the bulk, is generated from thermal plant — oil and some coal.
The potential for more renewable energy use and deployment in Mauritius is a focus of debate — just like the UK. The market economics and controversy are very much a current focus, as the Mauritius government considers its options, including the prospect of subsidies from the African Development Bank, for another coal-fired power station.
In terms of overall energy use, so much more can be done with energy efficiency. Mauritius is now beginning to look at a lot more development in this area and is even adapting many UK schemes. Hopefully, they have the advantage of seeing where we may have gone wrong with some of them!
Mike Malina is director of Energy Solutions Associates and the author of Delivering Sustainable Buildings published by Wiley- Blackwell. Readers of MBS can get a 20% discount using the code VBB09 at the link below.
A huge range of services is controlled by the BEMS in the headquarters building of the Mauritius Commercial Bank.
• 11 air-handling units
• Monitoring of a Cristopia thermal energy storage system (chiller), making it possible to adjust peaks in demand. Energy is stored during off-peak periods and transferred for use when demand exceeds the installed cooling capacity. The thermal storage system is also charged in the day from the large amount of electricity generated from the solar photovoltaic farm on site.
• Integration with free-cooling control
• Optimising the use of fan-coil units
• Air quality control — with demand-controlled ventilation
• Monitoring of all water and energy consumption on site
• Optimising the capture of rainwater for controlled irrigation of the external landscape
• Monitoring electrical consumption on all the floors and in building-services plant areas
• Providing fire and security control and monitoring;
• Full utilisation and monitoring of the solarPV farm
• Maximising natural daylight linking with full lighting usage (zone lighting)