Solar heating and cooling solutions for buildings

Stephen White July 2017

ENERGY FLAGSHIP Solar cooling

Using solar radiation to drive a cooling process. Displacing the use of fossil fuel derived electricity that would otherwise be used in a conventional vapour compression airconditioner.

 Solar thermal heat driving a thermal cooling process  Solar photovoltaics driving a conventional vapour compression cooling process Cooling Demand Matches Solar Availability Why solar cooling? - Policy perspective 1. Reduce greenhouse gas emissions 2. Lower energy costs/ benefit the electricity system

(higher load factor/ lower tariffs) Demand (MW) Demand

Time of Day 35%

Why solar cooling? 30% – Owner perspective 25% 20%

compliant buildings (%) buildings compliant 15% 1. Reduce greenhouse gas emissions/ - lower energy costs 10% -5%

2. Increase asset value 0% IPEEC, 2014 • Access to environmentally aware (CSR) -5% tenants

Percentage increase in sale price for green buildings buildings forgreen price sale in increase Percentage -10%

• Point of sale rating disclosure code conventional with compared -15% Year of Study -20% 3. Response to government policy 2008 2009 2010 2011 2012 2013 2014 • Compliance with minimum renewable energy targets (development permission) • Eligibility for incentives

Solar cooling market

Total amount of installed Total SolarsystemsCooling Europein &the World

Mugnier,Source: & SolemJakob, Consulting 2012 / TECSOL IEA Roadmap vision of solar heating and cooling (2012)

Solar cooling accounts for ~17% of TFE cooling in 2050 Technology Approach

ENERGY FLAGSHIP Routes to delivering solar heat

Solar Thermal Solar Electric

Roof cavity Transpired Glazed air heater Combi System Solar PV

Thermal heat pump

Mechanical heat pump • Split system • DX Unit Combi-systems beget solar cooling systems? Solar PV or solar thermal – integration and backup

Backup Thermally Thermal heater storage tank Activated Cooling Machine

Hot water

Solar collector panels Routes to delivering active solar cold

Solar Thermal Solar Electric

Flat Plate Evacuated Tube Parabolic Trough Parabolic Dish Solar PV

Stirling cycle

Single- effect Double- effect Rankine Cycle absorption chiller absorption chiller

Mechanical compressor driven Adsorption chiller • Split system • DX Unit Desiccant • Chiller dehumidification “Solar [thermal/vapour compression] hybrid” cooling? Free (Solar?) Cooling

ENERGY FLAGSHIP Free cooling approaches

• Economizer cycle • Economizer cycle with direct Air or indirect evaporative cooling • Night purge ventilation

• Evaporatively cooled water circulation ? Sealed well insulated buildings • ? Ventilated adaptive comfort Water Night sky radiant cooling • Geo-exchange Dew point cooler Gives enthalpy reduction; not just sensible - latent switch

Source: Oxycom Extending the economy cycle season

BrisbanePerth Dew point coolers entering the market Implications

• Smaller temperature differentials = larger air flows • Better suited to applications such as • Tempered air • Underfloor cooling • Chilled beams/ceilings (for evaporatively cooled water) • What level of duplication of infrastructure is required for peak demand? Solar PV Driven Cooling

ENERGY FLAGSHIP Systems emerging on the market Some indicative (only) information

Adapted from Mugnier and Mopty, IEA Task 53, 2016 Separate PV and AC (grid acting as buffer) vs Connected PV and AC (off-grid/ self consumption)?

Is this “Solar Airconditioning” or ”Solar AND Airconditioning” ? Potential benefits (beyond simple energy savings) Electricity system Consumer benefit Disadvantages benefit 100% off grid solar • Reduced peak Residential: • Wasted PV/AC with demand • leave it permanently electricity if separate AC • No reverse on = guilt free luxury airconditioning backup power flow Commercial is not required • Safety • Solar cooling efficiency • Needs batteries • Voltage increase at part load to manage • Slow ramp rates I don’t need to inform my fluctuations electricity utility • Reduced peak 100% Solar PV self I don’t need to inform my Wasted electricity demand consumption with electricity utility if airconditioning • No reverse grid backup is not required power flow Solar PV self Reduced peak Get full value for consumption with Lack of advantages demand electricity grid export/import Solar thermal driven cooling

ENERGY FLAGSHIP Solar thermal technology options

(By heat source temperature)

Performance

atm

P Water at Water Solar thermal collector efficiency Absorption chillers (predominantly LiBr/water) (Mature technology, chilled water output) Coefficient of Required Heat Chiller Availability Performance (COP) Source Temperature Single Stage 0.6-0.75 80-120ºC Good. Also ammonia Two Stage 1-1.3 160-180ºC Large systems (>100kW) Three Stage 1.6-1.8 200-240ºC limited

Broad NH3 /water

Century Carrier

Yazaki, Japan Robur, Italy (35 - 175 kW) (35 - 88 kW) EAW, Germany AGO, Germany (30 - 200 kW) (50 - 500 kW) Kawasaki Thermax Shuangliang York Adsorption Chillers Mayekawa (50 - 350 kW) Invensor (7 - 10 kW) Sortech (8 - 15 kW)

Mitsubishi Plastics (10,5 kW) Bryair (35 - 1180 kW) Desiccant dehumidification

60°C 35°C 7.0 g/kg

14g/kg ~200Pa 56°C 35°C 21g/kg 14g/kg 80°C

Electric heater or Gas heater  Suitable for solar pre-heat Selection considerations Absorption Adsorption Desiccant Hazards  Corrosive fluid  Inert solid media  Inert solid media  Crystallization Performance  Best COP  Works at lower  Works at lower  Poor at low temperature temperature temperatures  Lower COP  Free part load cooling ? Depends on conditions Heat  Cooling tower ? Cooling tower  No cooling tower rejection preferred Size/weight  More compact  Bulky and heavy ? Bulky but light Maintenance  Solution chemistry  Easy  Atmospheric pressure  Cooling tower  Cooling tower  Robust Cost  Comparable with  Expensive ? Probably most conventional (at scale) economic Co-benefits ? Ventilation Some likely combos

Air collectors → - Heating and desiccant dehumidification

Flat plate collectors → - Desiccant or adsorption system

Evacuated tubes → - Single effect absorption chiller

Concentrating collectors → - Double effect absorption chiller - Air cooled food refrigeration Indicative Performance

Electric Thermal 1 unit of Sun Low Efficiency High Efficiency Low Efficiency High Efficiency (air cooled) (water cooled) (single effect) (double effect)

Driving Energy 0.2 0.2 0.5 0.5

Cold (heat) 0.6 (0.8) 1.2 (1.4) 0.35 (0.85) 0.6 (1.1) Thermal systems are ideally integrated

Large Hotel Large Office Buidling 1% 13% 54% Air Conditioning 49% Air Conditioning 29%

Lighting Lighting Laundry Office equipment 1% Other 14% 37% Other Hot w ater 2%

Medium Size Hospital

20% 39% Air Conditioning

Lighting

Laundry

15% Other

8% Hot w ater 18% Cost competitiveness (example installed systems)

Neyer, Mugnier and White, 2015 Cost of energy savings compared with PV Sensitivity to buffer tank size , collector area and chiller size

Hotel in Madrid (3050 m2 floor area), “advanced” flat plate collectors and single effect absorption chiller Technical Integration

ENERGY FLAGSHIP Average Hobart diurnal profile

Summer Winter Average Townsville diurnal profile

Summer Winter But every day and every hour is different Storage and/or backup required Generic flow-sheet for matching an intermittent heat source and a variable demand for cooling

Cooling Tower

Solar Collector

Evaporator (+possible backup AC) Ten Key Principles Principle 1: Choose applications where high annual solar utilization can be achieved • Is there a load in the shoulder season? • Can solar be the lead with conventional peaking?

Principle 2: Avoid using fossil fuels as a backup for single effect ab/adsorption chillers

Principle 3: Design to run the absorption chiller in long bursts • If in doubt oversize the field not the chiller

Principle 4: Use a wet cooling tower where possible The Key Principles (con)

Principle 5: Select solar collectors that achieve temperature even at modest radiation levels

Principle 6: Keep the process flowsheet simple and compact

Principle 7: Match storage temperature and hydraulics with the application

Principle 8: Minimise parasitic power

Principle 9: Minimise heat losses

Principle 10: Apply appropriate resources to design, monitoring and commissioning Building Integration

ENERGY FLAGSHIP Bolt on or fabric integrated? • Reduced materials • Achieving core building duplication functionality • Improved aesthetics • Maintaining performance • Diverse product range

Lichtblau et al 2010 IEA Task41 categorization

Farkas, 2013

Source: Monier

Source: SOLID And other functions

IEA Task41 Transpired air collectors The attic - To suck or blow? That is the question Impacts of orientation and tilt angle Output per kW of panel purchased vs Output per m2 floor plate area Near horizontal panels don’t care about orientation Precinct Integration

ENERGY FLAGSHIP Zero Energy Precinct Example

• 151 Units • 11kV connection – Private network – No backflow • Residential demand – 550 kVA peak demand – 780 MWh/annum • PV potential from available roof area – 2740 MWh/annum Going solar 100%electricity Normalised Power Normalised Power ? More More generation capacity , Add battery storage, or Shift demand

Export somewhere somewhere or stored Needs to be transported • • Winter • • Summer the samedemand asaverage Exportat middayis approximately Nettshortfall daily than averagedemandatmidday around Exporting Nettsurplus daily 3 times more electricitytimes more (shifting (shifting to myneighbours) Examples

ENERGY FLAGSHIP SolaMate air heater example BlueScope PV/T example

NE Orientation

SW Orientation

Sproul and Farschimonfared, 2016 CSIRO residential hot water, heating and cooling product

 Provides cooling even when the sun is not shining  Low temperature heat source requirement  No cooling tower required (but does require water)  Positive pressurization of building Observations: Rowes Bay operating by itself Observations: Operating in tandem with peak smart Around the cities

Total comfort solution (% of hours) Total solution

as is Partial/hybrid cooling Partial/hybrid Large ESCO systems make economic sense • Wide variety of reported capital cost numbers

- lets say ~US$2,500 / kWcooling installed • Even better when there is a high DHW load =2.5 m2/kW

United World College, Singapore • 1575kW single effect absorption chiller • 3900m2 flat plate collectors with transparent teflon sheet • 60m3 storage at ~88°C

S.O.L.I.D • ESCO financing . =15 L/m2

Some absorption chiller installations in Australia

Source: ECS SERM building, Montpellier (France), 2010 TECSOL: engineering company District heating and cooling • 900 kW gas heating Building A : 11 000 m² - offices and shops • 700 kW chiller Building B : 10 600 m² with 167 dwellings

Montpellier Heating and AXIMA : Company in charge System net utilities of the works => System owner Buildings situation System selection

Application - Hot water preheat (all year round) - Autonomous solar cooling (when hot water temperature is high enough)

=6.9 m2/kW Selection - 240 m² double glazed flat plate collectors (Block A, limited by roof area) - solar circuit in drainback mode (with water glycol + HX) - 35 kW absorption chiller - 1500 liter hot buffer storage tank for the chiller (Block A) - + 10 m3 DHW storage capacity in Building B for dwellings) =43 L/m2 Schematic

Hot water gives year round solar utilization

DHW Heat Demand Heat DHW Solar Collected/ Heat Solar

Month Case study performance

Solar Parasitic Electrical Solar Collected Solar DHW Cooling electricity Seasonal Irradiation solar heat Production Production consumption Performance (kWh) (kWh) (kWh) (kWh) (kWh) Factor* (-) Jan-14 14,214 4,092 3,734 0 190 19.7 Feb-14 21,409 6,789 6,435 0 218 29.5 Mar-13/14 37,977 13,153 12,504 0 308 40.6 Apr-13 33,255 12,236 11,588 0 290 40.0 May-13 47,124 17,350 16,478 0 380 43.4 Jun-13 53,349 13,236 7,497 2,765 902 13.4 Jul-13 55,769 16,639 11,311 3,983 1190 13.6 Aug-13 48,656 12,467 8,628 1,970 840 14.2 Sep-13 37,744 10,513 9,316 676 554 18.9 Oct-13 24,645 8,541 7,843 0 240 32.7 Nov-13 17,309 5,133 4,789 0 220 21.8 Dec-13 15,164 4,341 3,851 0 157 24.6 TOTAL 406,616 124,490 103,974 9,394 5,489 21.5 TAFE commercial kitchens demonstration • Unique solar desiccant cooling design • Flat plate/ 2-rotor desiccant cooling • Solar hot water • Worlds largest solar desiccant cooling system =5 m2/kW 2 • 80 kWth =23 L/m • 400m2 collectors, 9000 litres Preheating water and precooling air Pre-cooled air out

Ambient air in Novel two wheel intercooled desiccant wheel system Solar hot water heating contribution

• Preheating cant heat the ring main Solar space heating and cooling contribution

• Evaporative cooling not included/ valued (despite doing the bulk of the cooling) • Temperature not always available to run the DEC Conclusion

• Solar cooling makes intuitive supply/demand sense • It can add to the value of the building asset • Solar PV driven systems are emerging on the market but manufacturers and electricity utilities need to work together • A wide variety of thermal technologies and solar thermal collectors have been demonstrated but work best satisfying integrated building thermal needs Conclusion • 10 Principles for good integration • Year round solar utilization • Integration with backup systems • Good quality solar collectors • Energy only economics are ok at large scale and for hot water lead • Desiccant cooling has cost, maintenance and part load advantages, but is probably not well suited to providing a 100% solution (but nor would you expect a 100% solution from intermittent solar) • But don’t forget low-cost building-integrated solar air heating options too Thank you Energy Technology Stephen White Energy for Buildings Manager t +61 2 4960 6070 e [email protected] w www.csiro.au/

ENERGY TECHNOLOGY