Churches of Christ New Queensland Head Office
Churches of Christ Queensland
National Construction Management
Churches of Christ is an established not for profit organization operating a broad range of community based services. With a long established base in Brisbane suburb of Kenmore, the organization is embarking on a staged redevelopment of this site which will see a community living, short stay accommodation and aged care facility eventually developed. Stage one of the renewal is the building of their new head office.
Churches of Christ in Queensland has the environment and sustainability at top of mind and is aiming for the highest possible energy efficiency rating with the development. The new head office building will feature a large solar panel array, geothermal air conditioning, photovoltaic energy generation and even provision for electric vehicles.
Geothermal Air Conditioning
To accommodate project requirement, QPS Geothermal delivered a 500kW central plant system, offering both heating and cooling as well as heat recovery for potable hot water. A high level interface was required for integration into building management system.
Works undertake were to Ashburner Francis specification as summarized below.
- Installation of fully operational central geothermal plant for chilled and hot water.
- Installation of heat recovery for potable hot water. Including provisioning of water circulatory lines to future build
- location. Single point chilled and hot water connections provided for mechanical contractor.
- Provision of sub mechanical switch board for single point connection by mechanical contractor.
- Provision of controls interface for Building Management System with single point connection for controls contractor.
1. Geothermal Loops
Works commenced in March 2015, with a total of 50 geothermal loops installed, 32 of which were located beneath the building, QPS Geothermal deployed two specialist drilling rigs for work to accommodate program requirements. Ground conditions encountered were basalt with layers of quartz requiring down the hole hammer drilling methodology to be deployed.
All GeoAir loops were installed with 8m separation. QPS Geothermal worked closely with the head contractor prior to commencement developing a coordinated services drawing to remove any in ground services conflict. All in ground works were programmed to maximize on site efficiency given works were on critical path.
Horizontal Line Runs
Geothermal loops were connected to plant location by way of excavated trenches at one meter below surface. All lines were installed within protective insulation and warning tape above lines. All excavated tranches were backfilled with sand.
All installation works were undertaken under controlled quality management, with installed lines vacuum and pressure tested prior to backfill. Lines were terminated within plant room for future connection to geothermal plant.
2. Geothermal Plant
Central plant was installed with a total cooling capacity of 500kW and heating capacity at 160kW. Located within designated plant area in basement, GeoAir plant replaced conventional chiller and boiler configuration. Total plant area is at 8200 x 3300 inclusive of service space. With each heat pump operating at 51db and requiring no ventilation, the installation did not require external plant, roof top platforms or cooling towers.
QPS Geothermal provided a mechanical sub board for single point connection by mechanical contractor. Sub board was located adjacent to geothermal plant.
High level interface was required for installation with interface into building management system. Using a centralized PLC, the GeoAir controls interface directly into building management system through BacNet protocol. Providing full automation and integration, controls system also provide real time data on all aspects of system operation.
Single point connection was provided for controls contractor with touch screen display.
Potable Hot Water
Geothermal plant connected to potable hot water to building via heat recovery exchangers installed in series. Provision for future supply to residential buildings is via circulatory lines installed to location as per drawings.
Passive hot water production will provide significant future operating benefits for facility.
GeoAir system as installed is operating at a total plant co-efficient of performance of 7.0. With 25 heat pumps at 20kW each installed, the plant has the ability to operate with only 4% of the total plant operating.
This modular nature of the installation provides significant part load efficiencies of the plant contributing significantly to the total operating efficiencies.
GeoAIr Installation Design Parameters
- Reduced electrical infrastructure was required for project significantly reducing associated costs
- Significantly reduced operating costs of air conditioning plant will provide benefit for organization over the life of occupancy
- No external plant removed need for rooftop plant and external plant enclosure removing associated build costs
- System offering both heating and cooling removes total plant on site offering ongoing maintenance costs
- Compact nature of plant reduces spacial requirements within building allowing usage for other purposes
- Waste heat from system provides potable hot water passively for building. Provisioning for future aged care accommodation to be built on site will provide passive potable hot water for this facility