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)