ENERGY RETROFITTING TORONTO MURBs: AIR-SOURCE HEAT PUMPS OPERATING IN ENCLOSED BALCONIES

Transcription

1 ENERGY RETROFITTING TORONTO MURBs: AIR-SOURCE HEAT PUMPS OPERATING IN ENCLOSED BALCONIES Presented by: Marianne Touchie, Toronto Atmospheric Fund and University of Toronto Contributing Authors: Kim Pressnail, University of Toronto Ekaterina Tzekova, University of Toronto

2 Outline Need for energy retrofits in MURBs Proposed retrofit strategy Modeling approach Results and discussion 2

3 The need for retrofit Aging Mechanical Systems Minimal Thermal Resistance Uncontrolled Air Leakage Thermal Bridging Image source: Tower Renewal Guidelines 3

4 Ventilation and Space Conditioning Pressurized corridor ventilation system

5 Ventilation and Space Conditioning Dynamic pressures (mechanical, stack and wind) + Loose envelope and interior partitions = Uncontrolled air flow Balanced? Infiltration Exfiltration 5

6 Proposed Retrofit Strategy Apartment Thermal Buffer Zone Exterior DHW and Space Heating ASHP HRV Image Source: NRC Evaluation Report CCMC R Lumon Glazing System 6

7 Modeling the Retrofit Strategy equest EnergyPlus Whole-Building Estimate Energy Reduction Factors Model Output Processor Image Sources: equest, EnergyPlus, M. Touchie 7

8 Whole-building Model Sub-hourly buildingand suite-level energy use Local climate 8

9 Whole-building Model Suite interior conditions Relative Humidity (%) South-facing suite Interior Dry Bulb Temperature ( C) ASHRAE Standard Temperature and RH range from CBE Comfort Tool: smap.cbe.berkeley.edu/comforttool 9

10 Suite-based operation in laboratory Thermal Buffer Zone Apartment 10

11 Suite Model Based on actual observed COP ASHP Power Consumption (W) Test Time (sec) COP Manufacturer s COP Overall COP Exterior Temperature ( C) 11

12 TBZ Temperature Drawdown Air Temperature ( C) Hours TBZ - ElecBB TBZ - ASHP Exterior Temp TBZ - ElecBB TBZ - ASHP Apartment Heating Demand (W) 12

13 Determine Net Heat Pumped Cooled Floating TBZ (ASHP TBZ operating) Effective Solar Gains + Heat transfer to/from TBZ with ASHP operating - Heat = lost Heat from Apartment available to to be pumped TBZ from TBZ = Net heat pumped by ASHP hybrid Image Sources: M. Touchie, Tower Renewal Guidelines 13

14 Model Output Processor 14

15 Modeled Scenarios Baseboard Heating ASHP (ambient exterior) Baseboard Heating ASHP (ambient exterior) ASHP (TBZ) 15

16 Heat Delivered to Suites South North Overall COP ElecBb 1 ASHP 2 ext 3 4 ASHP Hybrid ElecBb 1 ASHP 2 ext 3 4 ASHP Hybrid High Mid Low Ext High Mid Low Ext ASHPext ASHPtbz ElecBB ASHPext ASHPtbz 16

17 Suite Model Results 17

18 Whole-Building Results - EUI Annual Energy Use Intensity (ekwh/m 2 ) Baseboard Case (HydronicBB) Heating 34% 39% TBZ - ASHPext TBZ - ASHPhybrid Natural Gas Electricity 18

19 Whole-Building Results CO 2 Emissions Annual CO 2 Emissions Estimate associated with total building energy use (tonnes) 1,600 1,400 1,200 1, Base Case (HydronicBB) 41% 45% TBZ - ASHPext TBZ - ASHPhybrid Natural Gas Electricity 19

20 Whole-Building Results Whole-Building Savings Energy 39% Cost 3% Emissions 45% 20

21 Other considerations Occupant control over temperature Limit over-heating Direct heat to where it is needed To improve performance: Compartmentalization Occupancy sensors Challenges: System design Equipment maintenance 21

22 Conclusions Significant reductions in overall energy use possible Alternative heat delivery system if current system is at end of service life Can also be applied on a smaller scale for central systems (e.g. central heat recovery or solarwall) Image Source: University of Toronto 22

23 Acknowledgements Natural Sciences and Engineering Research Council Toronto Atmospheric Fund Neil B. Hutcheon Bequest 23

24 For further information Marianne Touchie Touchie, M.F., Pressnail, K.D. Testing and Simulation of a Low-Temperature Air-Source Heat Pump in a Thermal Buffer Zone, Energy and Buildings 75 (2014) pp Touchie, M.F., Pressnail, K.D. Using Suite Energy-Use and Interior Condition Data to Improve Energy Modeling of a 1960 s Multi-Unit Residential Building, Energy and Buildings 80 (2014) pp Touchie, M.F., Pressnail, K.D. Evaluating a Proposed Retrofit Measure for a Multi-Unit Residential Building which Uses an Air-Source Heat Pump Operating in an Enclosed Balcony Space, Energy and Buildings (In Press) Thank you! 24