In 2001, The State of Environment report clearly shows the buildings add negative impact to our natural environment up to 32% of the world’s resources, including 12% of the fresh water and up to 40% of the world’s energy. Buildings also generate 40% of waste to landfill and 40% of air emission.1 Ecologically Sustainable Design (ESD) was such a trend nowadays. What is sustainability? In 1990, Australian Government defined ESD as:
‘using, conserving and enhancing the community’s resources so that ecological processes, on which life depends, are maintained, and the total quality of life, now and in the future, can be increased’.2
Based on a number of criteria, including energy and water efficiency, quality of indoor environment and resource preservation, the Green Building Council of Australia has formed the Green Star rating tool for evaluating the environmental performance of new and refurbished office buildings. In this report, a comparative study of the Alan Gilbert Building, 40 Albert Road and Council House 2 will be carrying out. These buildings are considered a new benchmark for sustainable buildings in Australia and achieved 5 stars Green Star rating. This case study investigates the indoor environment quality (IEQ) of the air-conditioning system whether is full or mixed mode and also other sustainable features.
Alan Gilbert Building
Alan Gilbert Building is situated on Grattan Street. It is an example of an innovative green building product in Australia, was awarded “RAIA sustainable building award” in 2002. This 17,200 square meter building is on 9 levels and consists of classrooms, lecture and theater halls, bookstore, cafÃ©, and also six
1 OECD (2003) Environmentally Sustainable Buildings: Challenges and Policies. A report by the OECD
storey of office area. It is design by Metier 3 architect with a requirement that architect must have first consideration on ESD within the budget. This building has a good presentation on the HVAC system, solar power generation and other Environment Sustainable Design features.
40 Albert Road
40 Albert Road, South Melbourne is introduced as the first office refurbishment that exploits cutting edge sustainable design with futuristic alteration. Szencorp Company provides expertise in providing sustainable business. This building consists of four office levels and two car park levels, is the new headquarters of Szencorp Company that utilized $3,500,000 for the refurbishment cost. 3 This 1,200 square meter building has been awarded a 6 Star Green Star- Office Design V1 rating which gives the project “world leadership” status.4 The innovation of the sustainable design is demonstrated in advancement of the gas engine driven air conditioning, thermal comfort, ceramic fuel cell that generates power and the dehumidification system.
Council House 2
Council House 2 is situated at the corner of Little Collins street and Swanston Street. This 10-storey office building with 1,316 square meters has achieved a 6 Star Green Star- Office Design V1 certified rating. 5 The This total building cost is $51.045 million and it is estimated that in ten years time the sustainability features will have paid for themselves. 6 The key areas of achievement are features shower towers, wind turbines, chilled ceiling panels as cooling system, water mining plants, vertical garden and low VOC products.
3, 4 http://www.gbcaus.org/newsletter_archive/2005nov.ht
3. Indoor Environment Quality (IEQ)
Alan Gilbert Building
The system used in Alan Gilbert building is heating, ventilation, air-conditioning system (HVAC). This purpose of HVAC system is to provide thermal comfort, good indoor air quality and reduce air infiltration within the interior by control the interior temperature included heating/ cooling and fresh air provided in interior spaces. There are 3 types of air conditioning system used in office building in Australia. The centralized ducted air system is most commonly use in large office building which primary movement of heat around the building is via heated and cooled air. The centralized fluid base system are commonly use in office building which use fluid or refrigerant to move heat around the building. The decentralized system is fairly using in small office which heating and cooling is conducted locally, with little movement of heat around the building. 7 There are 3 types of centralized ducted air system which is constant volume system (CV), dual duct system and variable volume air control system (VAV).
Alan Gilbert Building is using VAV system and central air handling system. The HVAC is a low pressure system that incorporates the outside air temperature and quantity. VAV systems vary the air quantity rather than temperature to each zone to maintain the appropriate room temperature. Fan energy is saved when the volume of air handled by the fan is reduced. Air volume control is accomplished by installing modulating dampers, or in some cases, an air valve, in the supply duct to each zone. As the room temperature demand becomes satisfied, the thermostat signals the damper to move the supply air zone valve toward the closed position.
When zone valves are throttled, the static pressures in the supply duct changes. A static pressure sensor located in the supply duct senses the static pressure change and either increases or decreases the airflow from the source, using variable speed control or dampers on the main air supply fan.
A key component in the VAV system is the air valve. It is commonly installed inside an insulated sheet metal box suspended in a ceiling plenum. The air valve has a damper that regulates the air flow in response to the room’s thermostat. A multi-port pressure sensing ring provides both accurate airflow sensing and control in response to duct static pressure. 8
Figure 1: How VAV system works
The VAV system has the best result in energy saving because it can avoid the unnecessary heating and cooling by control the central air handling fan speed to maintain the pressure of air flow. However, this system cost more than normal air-conditioning system due to its complexity and a good quality control. According to the Australia Government Green House research: as long as the minimum air flow pressure is much smaller than the maximum air flow, and the VAV system is operating probably, thus the additional control complexity is not necessary, such as the duct temperature sensor. The common problem which is the sound pollution and the system required more spaces to accommodate the plant and equipment.
40 Albert Road
Internal air quality is the main consideration in this building. For instant, the thermal comfort is accomplished by combining natural ventilation with mechanical cooling and heating. The opening windows and dampers is operated mechanically allow fresh air in and drive out used air. Natural ventilation is automated and is fully utilized the internal and external environmental conditions on the eastern and western faÃ§ade with fresh air and mechanical cooling and heating is supplied by ceiling-mounted fan coil unit.
Figure 2: Dehumidification process
DryKor conditioning unit is ‘first’ introduce into this refurbishment project. With the advancement of processing natural desiccant absorption of water vapor from the air ducted the humidity outdoors, the DryKor conditioning unit is non toxic and non hazardous while dries and cools the office space concurrently and it will not vaporize and is not effected by common airborne contaminates. The system is expedient because of eliminating the pipes, pumps and drainage system. The
figure 2 http://www.nrel.gov/technologytransfer/entrepreneurs/pdfs/17_drykor.pdf
system innovative technology employs a latent heat pump fuelled by the hygroscopic process. The more moisture in the air, the more efficient the DryKor process, thus the system save greater cost compare to the traditional equipment. Further that, “Sick Building Syndrome” problems relate to poor indoor air qualities are reduced because up to 94% of micro-organisms and 77% of particles greater than 5 microns are removes during the process. 9
The building use a gas engine driven air conditioning rather than the electric motor conditioning unit. The Mitsubishi gas engine driven air are the first for Melbourne office building. The system is selected because it allow for capacity control by a fully module compressor speed with their ability to trim down peak demand loads on the electricity grid, allowing the peak tariff usage of the company are reduced to a great amount. The system bypasses the use of grid electricity usage that contributes to the global climate change. In that case, the need for the infrastructure upgrade can be reduce because there is substitute choice for energy consumption. The benefit of using this system is the lower coefficient of performance (COP) inherent in this machine powered by an internal combustion engine rather than an electric motor and the result is lower overall carbon emissions produce by this building.
All new material that introduce in the refurbishment process have a serious consideration on the internal air quality. For example, volatile organic compound (VOCs) emission levels from carpets, adhesives and sealants in the office building are minimized. Low VOC paints are also applied on 95% of painted surface in the building. All furniture that is made from wood is low in formaldehyle emissions while pollutions from printers and photocopiers are filtered by a special exhaust riser. 10
Council House 2
Council House 2 demonstrates an extraordinary level of innovation in environmental design. In CH2 air that supplied to the office spaces will be 100% fresh air and will not recycle any air. The filtered fresh air drawn from roof level, supplied using the south ducts and exhausted using the north ducts. The minimum fresh air requirement is the major part of designing the ventilation system in this building. CH2 set its minimum fresh air requirement to 22.5litres/second/person while the Australian Standard requires 7.5litres/second/person. This increasing amount of fresh air constantly reduces the low productivity and the sick building syndrome. The ventilation system for CH2 is a displacement ventilation system which delivers fresh air into the office space through individually controllable vents in the floor. Warm air that generates from the occupant and equipment will rise and exhaust offs the space through vents in the ceiling. There is a carbon monoxide (CO) monitoring system that controls the ventilation system by deliver outside air into the space without mixing or recirculating air back at the central air handling plant. 11
CH2 put more effort on cooling rather than heating the building. The building air-conditioning system design to capture and use the heat that generates from the occupant and equipment thus the major energy consumption is focus on cooling. There are five shower towers that use falling droplets of water to cool air will be seen from Little Collins Street. Fresh air will be
Figure 3: How shower tower works
figure 3 http://www.melbourne.vic.gov.au/rsrc/Images/CH2/diagrams-revC_07.jpg
drawn in through louvers at the top of the shower tower by the falling water which displaces air in front of it. The air will be cooled by evaporation from the water shower within the tower. The cool air is supplied to the shops below and the cool water is supplied to a Phase Change Material (PCM) tank in the basement.
The PCM will be much like a battery that stores coolness for the rest of the building when required. PCM refers to the process of a material changing from a liquid to a solid or vice versa. Water cooled by the
Figure 4: Cooling effect shower towers will travel through the tank and freeze the PCM. There will be a separate stream of water pass through the tank to be chilled, travel through the chilled ceiling panels and chilled beams to cool the building then run back to the tank to begin again. Radiant cooling is delivered from chilled ceiling panels fixed to the ceiling and chilled beams in front of the windows into the workspace at around 18ºC. This replaces traditional VAV system that uses fans to blow air directly to the occupants. 12
figure 4 http://www.melbourne.vic.gov.au/rsrc/PDFs/CH2/cooling.jpg
Natural ventilation cools the building late at night using a system referred as night purging. Windows on the north and south facades will open to allow fresh air to enter the offices, flush out warm air and cool the building. The windows will be close when sensors detect high winds and rain or higher
Figure 5: Night purge process temperatures. Due to the high thermal mass, the 180mm thick pre-cast concrete ceiling will store the coolness from outside air during the night purge process. During the day, the concrete ceiling is heat up by the day’s activities and is release into the cool night air. There will be thermometers that monitored the temperature of the internal and external air so maximum energy efficiency will result.
4. Other ESD Features
Alan Gilbert Building
There is 426 meter square of 148 panels of 8 different sizes of photovoltaic panels (PVs) located on the two top levels on the building of the north-facing faÃ§ade. “Photovoltaic effects’ is a physical process that turns the sunlight that captured in the photovoltaic panel and convert into direct-current (DC) electricity. Sunlight has an energy content of 1kW per square meter, typical Photovoltaic Panel today achieves between 10% and 15% conversion. 13 The electricity supplied to the building from the electricity grid provide up to 40kW of
figure 5 http://www.melbourne.vic.gov.au/rsrc/Images/CH2/diagrams-revC_07.jpg
electricity. This ideal location to put the PV panel is the most important consideration as it will affect the effectiveness of the system. For instant, in Alan Gilbert building, the angle is 63° to have a longer direct sunlight at daytime.
Due to the projects’ budget and the cell colour, polycrystalline cells were selected. The PV cells have been laminated into heat-strengthened glass panels and integrated to the cladding.
The ESD features demonstrate in Alan Gilbert building other than the HVAC and PV system. The large window glazing north facing faÃ§ade have a great thermal insulation on summer and have natural sunlight during the winter. The glazing chosen are low emissive (Low E) because they reflect long wave radiation and emit low levels of radiated heat into the building. Sun shading is designed at ground floor and first floor. The west faÃ§ade was carefully designed by reducing window areas with a feature projecting vertical blade on the deep inset multi-level balcony. While the east faÃ§ade layered with large framed grid of blades and ledges to give shading from morning summer sun. To avoid unwanted penetration of morning and late evening summer sun, the south faÃ§ade have a large blade and ledge grid on a smaller scale. 14 An 11,000 litres of rainwater storage copper tanks in the roof plant are used for toilet flushing. To reduce energy consumption and cost, T5 lighting system will automatic switch off when it is not use.
40 Albert Road
A centralize computer management system use to control and operate all the equipment in the building. Single interface for passive and active control system, lighting control system, security and other automated systems are provided by the Building Management System (BMS). Information gathered from the weather station is integrates from a high level interface of BMS that monitors the outside air pressure, wind velocity, direction, rainfall, temperature and humidity.15
14 Sun control, article from Lindsay Johnson
To maximize the proper way of using the facilities, a Building Users’ Guide will provide to the tenant with all necessary instructions. This building has the most advanced and transparent building performance monitoring system in Australia that monitor real time building performance. The Managed Lighting System (MLS) monitored the temperature, humidity, daylight, lighting levels, air quality and occupancy in each floor of separated zones. Energy efficiency is achieved by maintaining services only in the zones that are occupied. 16
Ceramic fuel cells is use to provide direct current (DC) electricity using chemical reactions instead of combustion reaction that contribute to the global warming.
Fuel cell is unlike batteries, it cannot store electricity energy or rechargeable. It can continuously generate electricity as long as they have a supply of fuel and air. This system integrates with the hot water system with the combination of heat and power that generate approximately 12MWh per annum of majority production of domestic hot water. Every 2.5KWh of energy input will generate 1 KWh of heat and power to the building. Thus, this building will be the first ceramic fuel cell in commercial operation in Australia that will provide 100% of hot water requirement within the building. 17
There is a central vacuum system that operates during office hours which are more effective (40% faster) and less noisy than portable vacuum machine and it increase occupant health and wellbeing by maintaining the cleanliness, reduce allergic mould, moisture problems and dust. Energy consumption of lighting and air-conditioning reduce because cleaning process can be carry during the office hours. Water management system achieved an 82% reduction in freshwater use while the sewerage discharge is reducing to 72% over the industry average. Water usages are reduced by utilizing controlled flow showerheads and taps through sensor. Beside that, rainwater harvesting system store 4,400 litres if
rainwater and treated grey water are collected for toilet flushing. 18
17, 18 http://www.ourgreenoffice.com
Council House 2
There is a water mining plant that recycles black water from city’s sewers for non potable reuse. The water mining plant is located at the basement that draws 100,000 litres black water per day. The water is used for plant watering and toilet flushing. Beside that, rainwater is collected and used for plant watering. There is also a solar hot water panels on the roof that provide 60% of the hot water. The louvers that clad on the east and a west facade was made up of perforated steel and recycled timber. There was also a vertical garden on the northern faÃ§ade that provides shading and increase the ambience. 19
Figure 6: Comparison of 3 building system
This 3 building has set a trademark as a new concept that provides sustainability in building design. The vision of these projects is to achieve the highest level of sustainability, perfect environment outcomes for occupants, commercial viability that demonstrate the sustainable developments and act as a platform for development and commercialization of innovative Environmental Sustainability Design. The disadvantages are noticeably with the relatively high capital cost for ESD building services. The pay back for these projects is long. However, when one is considering the life cycle cost, it is actually benefited from it in a long run because this technology will become more common in the future and human being start to wake from the impact on natural environment.