Low Exergy Systems for High-Performance Buildings and Communities

Transcription

1 LowEx Phd Students workshop 18th October 2010 Low Exergy Systems for High-Performance Buildings and Communities Tekn. Dr. Dietrich Schmidt

2 page Objectives Energy savings and reduction of CO 2 -emissions: By the use of low valued and environmentally sustainable energy sources for heating and cooling of buildings. Through utilization of the EXERGY concept

3 Quelle: VTT page Why exergy? - Matching of the energy quality of demand and supply Energy supply Energy use ource Energy quality q 1 0 Fossil fuels, electricity Low District temp. heating supply C55 C Low temp. supply Ultra low 55 temp C supply 40 C 1 Energy quality q 0 Appliances, Lighting Sauna Domestic hot water Space heating

4 Approach: Exergy concept matching the Quantity AND Quality levels of supply and demand Quantity Energy savings Quality use of low quality sources e.g. solar thermal heat, ground/air hea page

5 page Scope LowEx Activities Sustainable community systems Supply systems Building systems

6 page Analyses tools for LowEx systems Software tools for an energy/exergy assssment 7% exergy fraction of the energy

7 Analyses tools for LowEx systems page

8 page Benchmarking of system solutions Non renewable Power primary energy Cond. boiler, radiators. Biomass, floor heat. GSHP, floor heat.

9 page Benchmarking of system solutions Non renewable Renewable Power primary energy Cond. boiler, radiators. Biomass, floor heat. GSHP, floor heat.

10 page 1 Benchmarking of system solutions Renewable Non renewable energy Renewable Non renewable exergy fraction power primary energy / exergetic fraction Cond. boiler, radiators. Biomass, floor heat. GSHP, floor heat.

11 page 1 Benchmarking of system solutions Exergetic fraction of the primary energy power Limit LowEx Biomass, floor heat. Cond. boiler, radiators. GSHP, WP floor heat. Exergy demand of zone ideal

12 Low Exergy Buildings? Match quality levels of supply and demand by exploiting low quality, waste or environmental sources Passive house Q end = 70 kwh/m 2 a Q end = 16 kwh/m 2 a Q H = 15 kwh/m 2 a Q H = 60 kwh/m 2 a...no combustion in buildings...but LowEx buildings are not Passive House buildings Air heat recovery unit Source: ETH page 1

13 Low Exergy Buildings? minimize primary energy: by exploiting low quality, waste or environmental sources Passive house LowEx house 40% solar fraction Q end = 16 kwh/m 2 a Q H = 15 kwh/m 2 a Q end = 6 kwh/m 2 a H 40 Q kwh/m H = 40 2 kwh/m a 2 a Air heat recovery unit Ground source heat pump Source: ETH...no combustion and minimum high exergy (primary energy) input page 1

14 page 1 Building systems: Example (Switzerland) System integration COP Real : Range = 8-15 Goal: Average >10 Appropriate heat/cold emission systems

15 page 1 Building systems: Example Ground heat exchanger (mainly for cooling) Energy poles Source WH Zwickau, Germany Bore holes Horizontal heat exchanger Horizontal heat exchanger with capillary tubes Source City of Kassel, Germany

16 page 1 Seeking Low-Exergy Supply Structure for a Community Heating plant CHP Industry Waste heat Veolia Environment

17 page 1 Community case study: Heerlen (The Netherlands) - LowEx approach for the Mine Water Project distribution LT DH&C 3-pipes system demand Buildings suitable for use of low valued energy (LTH and HTC) supply Minewater Additional RES biomass, solar Integral system approach for the total built environment

18 Heerlerheide phase 1 Buildings Heerlerheide Centre H C R C 17 0 C C 2 Warm Wells Energy station Heerlerheide Centre HP HP C Intermediate Well Heerlen SON phase 2 Energy stations Energy buildings stations Energy buildings stations buildings Energy station Maankwartier HP C HP 2 Cold Wells page 1

19 Community case study: Heerlen (The Netherlands) 1 Exergy Efficiency [-] GSHP+LTH Gas boiler HP Minewater+LTH Air conditioning+ltc Passive cooling, HTC DEMANDS: Space heating / cooling and DHW demands PER (Primary Energy Ratio) [-] LTH= low temperature heating HTC= high temperature cooling page 1

20 page 2 Community case study: Oberzwehren (Germany) DEMANDS: Space heating and DHW demands SUPPLY OPTIONS: : - District heating (return) - Solar thermal collectors - GSHP, COP=4

21 page 2 Community case study: Oberzwehren (Germany) 1 Exergy Efficiency [-] Solar thermal, 40% solar fraction District heating 50/30 C GSHP COP = 4 Solar thermal, 80% solar fraction PER (Primary Energy Ratio) [-] - Exergy performance of solar thermal systems low due to required conventional back up - District waste heat: best exergy performance

22 Community case study: Parma (Italy) DEMANDS: Space heating, DHW demands AND electrical appliances SUPPLY OPTIONS: Heat: - District heating - GSHP (COP=5) - Solar thermal 60% fraction Electricity: 33% PV & 67% CHP (renewable) page 2

23 page 2 Community case study: Parma (Italy) Exergy Efficiency [-] PV District heating 50/30 C GSHP COP=5 CHP Solar thermal 60% solar fraction PER (Primary Energy Ratio) [-] - Renewable energy share in district waste heat gives best energy and exergy performance

24 page 2 Concluding remarks 1. Exergy demands for heating/cooling are very small -Energy demands are high. 2. Supply as low exergy as possible to the room space avoid combustion processes and minimize electricity input 3. Find suitable low-exergy sources in the immediate/local environment. 4. Development of system-components and their smart integration are necessary

25 Why exergy? Therefore: page 2 1. Exergy is not an universal indicator! But: based on thermodynamics 2. Gives it differences in building design? Yes: compared to forced air systems No: if low temperature systems considered 3. Good news: Not all existing buildings need to be passive houses! 4. Communities: Exergy diagram (PER) shows performance of supply options 5. Consider lifecycle costs

26 page 2 Final Annex 49 Conference The Future for Sustainable Built Environments with High Performance Energy Systems 19th-21th October 2010 Oskar von Miller Forum Munich, Germany