Small Council, Big Vision, Bigger Savings: The Transformation of the Riverina Highlands Building
Yale Carden (M.AIRAH, M.IGSHPA) and Cameron Hutchison (M.IGSHPA)
Presentation Overview
• The Small Council: – Tumut Shire and the Riverina Highlands
Building
• The Big Vision: – The Riverina Highlands Building Energy
Efficiency Project (RHBEEP)
• Geoexchange Project Cycle
• Bigger Savings: – The Story So Far
• Conclusions
Introduction
• Client: Tumut Shire Council
• Population: 11 000
• Elevation: 305 m
• Monthly Minimum: 1.2 C in July
• Monthly Maximum: 31 C in January
Location
The Riverina Highlands Building
• Built in early 1980s by Tumut County Electricity Authority
• NLA of 2326 sqm over 3 floors
• Brick, iron roof, single glazing, minimal insulation
• Tenants: Council, State Government Departments, Emergency Operations Centre
• Purchased by Tumut Council in 2008
Stewardship Commences
• 2008: First AC Audit
– Replacement required
• 2011: Level 2 Energy Audit
– January 2009 to October 2011
– Daily peaks of >200 kWh from June to August
– Monday winter peak from 0630 to 0800
– Daily peak in summer of 100-150 kWh from 1430 to 1700
Electricity Use Breakdown (2010)
Usage kWh pa Percent
Lighting 130 341 24 %
HVAC 283 302 51 %
Refrigeration -- --
Appliances 134 410 24 %
Pumps and Motors -- --
Hot Water 7621 1 %
Other -- --
TOTAL 555 673 100 %
Energy Audit: The Business Cases
• Upgrade and Retrofit Lighting (T8-T5);
• HVAC Retrofit / Upgrade; and
• Solar PV Installation (30 kW)
• Plus
– Installation of insulation;
– Power Factor Correction; and
– Metering Optimisation
The Big Vision - RHBEEP
• Reduce electricity
• Lead by example
• Educate others
• Future proof
• Build local capacity
The Big Vision - Finance
• Community Energy Efficiency Program (CEEP): $877 516
• Clean Energy Finance Corporation (CEFC): $1.18 million low interest loan
Transforming the HVAC
• Existing / original:
– Air cooled central plant with electric duct heaters
– Split DX units in meeting rooms, server room and Emergency Operations Centre
Transforming the HVAC
• Upgrade Options
– Optimise existing system
– Variable Refrigerant Volume (VRV) system
– Geoexchange / GSHP system
The Geoexchange Project Cycle
• Pre-feasibility and Concept Design
• In-situ Thermal Response Test
• Geoexchange Design
• Building Services and GSHPs
• Ground Heat Exchanger
• Pumping Strategies
Pre-feasibility and Concept Design
• Desktop Study Identified:
– Client Commitment
– Climate
– Car Park for Ground Heat Exchanger (GHX)
– Internal space suitable for GSHPs
Thermal Response Test
• Thermal Conductivity
• Thermal Diffusivity
• Mean Earth Temperature
• Practicalities
Geoexchange Design Process
• Building:
– Annual hourly load profile
• Ground:
– Thermal properties - TRT
• Distribution:
– Building services and GSHPs
• Integrate:
– Building annual heat flux with ground capacity
Geoexchange Design Process
• Finalise:
– GHX design re borehole quantity, depth and spacing
• Pumping:
– Optimise heat transfer and minimise pumping costs
Building Services and GSHPs
• Distributed ‘water to air’ GSHPs
• 26 GSHPs in individual zones
• DC inverter compressor
• Variable speed fans
• Modulating water valve
The Ground Heat Exchanger
• 35 boreholes at 92 m deep, 7 m spacings
• Bentonite / silica grout (enhanced)
• Reverse return manifolded as 5 sets of 7
• Material: PE100, DN40 (boreholes)
• Material: PE100, DN40-180 (manifolds)
• Electrofusion joints
The Ground Heat Exchanger
Pumping Strategies
• Low pressure drop
• No balancing valves
• 3 circulating pumps with VS drives (1 standby)
• Additional small pump for very low loads such as Emergency Operations Centre
Bigger Savings: The Story So FarSummary of Energy Savings Across the RHB (MWh)
Lighting HVAC Other Total
Baseline Data
121.9 267.1 142.1 531.2
Jan-May 2014
51.2 37.6 135.0 223.8
Savings
70.7 229.5 7.1 307.3
% of System 58 % 86 % 5 % 58 %
% of RHB 13 % 43 % 1 % 58 %
Bigger Savings: The Story So Far
• 86 % HVAC savings includes insulation and lighting upgrades
• Level 2 Audit predicted 79 % saving with geoexchange
• Does not yet include the heating season, which has predicted savings of 88 %
• Annual maintenance costs were ~$80 000
Bigger Savings: The Story So Far
• The simple economics:
– ~$217 00 in annual savings
– Simple payback is ~8 years
– Simple payback with funding is <4 years
– ROI is 11-12 %
• Increased plant room space
• Higher comfort levels
• Greater temperature and humidity control
Bigger Savings: The Story So Far
Conclusions
• The value of a big vision
• Power of a small team with a purpose
• A template for similar buildings
• Importance of finance structures
Finalist Awards
• AIRAH 2014 Award for Excellence: – Best HVAC and Refrigeration Retrofit or Upgrade (National
Award)
• Banksia Foundation:– Innovator of the Year (National Award)
• Local Government NSW: – Climate Change Action (State Award)
• Local Government Management Association Excellence Awards 2013: – Excellence in Environmental Leadership and Sustainability
(State Award)
• Office of Environment and Heritage Green Globe Awards:– Local Government Sustainability (State Award)
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