Building Energy 2014: PV and Heat Pumps by Fortunat Mueller


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Presentation on the possibilities for Net Zero building using a combination of Grid Tied PV and Ductless Mini Split heat pumps. from Building Energy 2014 Tuesday seminar

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Building Energy 2014: PV and Heat Pumps by Fortunat Mueller

  1. 1. Building Energy 2014 PV and Heat Pumps: Net Zero Heating Solutions Fortunat Mueller PE Co Owner ReVision Energy March, 2014 Professional design, installation and service of renewable energy systems.
  2. 2. Heat Pumps and Net Zero • Intro •Why Heat Pumps for Net Zero •PV Basics •Heat Pump Basics •Mini Split details •Design Processes •Working Example
  3. 3. Who is ReVision Energy? • Northern New England’s most experienced renewable energy • installer—more than 2,500 solar hot water & solar electric systems in Maine & NH. Expertly designed systems installed by our certified professional solar team. Master trade licenses and NABCEP certification carried in-house, supporting our full service mechanical contractor approach.
  4. 4. Locations : •Liberty, ME, Portland, ME , Exeter, NH •Serving all of Maine and New Hampshire and SEVT and Northern MA Professional design, installation and service of renewable energy systems.
  5. 5. Technical Competence • • • • • • • • Master Electrician’s License Master Plumber’s License NABCEP Certification (Thermal & PV) Maine State Solar Installer Certifications EPA Refrigerant License 2,500+ Systems Installed to Date Engineering in-house (P.E.) Depth of Experience
  6. 6. Define Net Zero Building A zero-energy building, also known as a zero net energy (ZNE) building, net-zero energy building (NZEB), or net zero building, is a building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site.
  7. 7. How do you get there? • NG plus HUGE PV to offset all source energy • Biomass + PV (wood or pellets) • Large Solar Thermal + PV • Resistive Electric + PV • Heat Pump + PV
  8. 8. Pellets + SHW + PV
  9. 9. SHW + PV + Resistive Electric
  10. 10. Heat pump as Lever for PV
  11. 11. PV + Heat Pumps
  12. 12. Mini Splits are all the rage… • Low(er) Cost? – Gas by wire for those without access • • • • No Combustion Air conditioning as a benefit Good fit for supplemental heat Path to net zero with PV
  13. 13. Why Heat Pumps • Part of a strategy to get off oil and lower heating costs –
  14. 14. Heat Pumps and Net Zero • Allow you to heat/cool efficiently with electricity which is easily produced renewably on site • By taking advantage of net metering, you can easily ‘store’ the electricity generated in the summer to use for heat in the winter.
  15. 15. Energy Security in Reach • Consider a very well built new home with an annual heat demand of 40 Million BTU’s per year – 2,000 sf ; R40/R60 insulation; Triple Pane windows; HRV • • To provide 40 MMBTU with a Heat Pump at an average COP of 2.8 requires approximately 4,185 kw-hr of electricity. To generate that amount of electricity in Maine requires about a 3.3 kW GTPV system. – ~200 sf of modules – ~$7,000 Net cost (after incentives) For that cost you are buying all the ‘fuel’ you’ll ever need to keep your house warm for life! That is pretty awesome.
  16. 16. In one hour enough solar energy strikes the earth’s surface to supply all energy demand for one year. Net Zero home in Lancaster NH.
  17. 17. • Putney School Field House in VT • Good building practice, GTPV and Air Source Heat pump combine to make a net zero building
  18. 18. Solar Electric Basics Proctor Academy, Andover, NH
  19. 19. PV System Components Photovoltaic modules convert sunlight into Direct Current (DC) electricity, which flows through cable to the inverter. Inverters accept the DC electricity produced by PV modules and convert it into Alternating Current (AC), which then feeds demand in the building or if there excess, feeds the utility grid.
  20. 20. Residential PV Systems
  21. 21. Ground Mounting Options
  22. 22. Inverter Replaces Batteries
  23. 23. Basic Solar Facts • 1000-1300 kwhr/kw in New England • 50-70 sf of modules per kW
  24. 24. Heat Pumps Basics • A heat pump is a machine or device that moves heat from one location (the 'source') at a lower temperature to another location (the 'sink' or 'heat sink') at a higher temperature using mechanical work or a high-temperature heat source
  25. 25. Thermodynamics 101
  26. 26. Temperature vs Heat •Temperature is a number. That number is related to energy, but it is not energy itself. •Temperature is a number that is related to the average kinetic energy of the molecules of a substance. •Temperature is a measure of the average kinetic energy of the molecules of a substance. An increase in temperature results in an increase in the kinetic energy of the molecules and an increase in thermal energy. It is fair to say that temperature and thermal energy vary directly, but they are not the same thing. •Heat, on the other hand, is actual energy measured in Joules or BTUs or other energy units. Heat is a measurement of some of the energy in a substance. When you add heat to a substance, you are adding energy to the substance. This added heat (energy) is usually expressed as an increase in the kinetic energies of the molecules of the substance.
  27. 27. Sensible vs Latent Heat •Sensible heat When an object is heated, its temperature rises as heat is added. The increase in heat is called sensible heat. Similarly, when heat is removed from an object and its temperature falls, the heat removed is also called sensible heat. Heat that causes a change in temperature in an object is called sensible heat. •Latent heat All pure substances in nature are able to change their state. Solids can become liquids (ice to water) and liquids can become gases (water to vapor) but changes such as these require the addition or removal of heat. The heat that causes these changes is called latent heat. Latent heat however, does not affect the temperature of a substance - for example, water remains at 100°C while boiling. The heat added to keep the water boiling is latent heat. Heat that causes a change of state with no change in temperature is called latent heat.
  28. 28. Sensible and Latent heating of water from ice to steam Adding Heat
  29. 29. 2nd Law of Thermodynamics • Says basically that physical systems tend towards equilibrium in terms of pressure, temp, chemical reactions. • Clausius statement : No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature. Commonly: “Heat flows from Hot to Cold”
  30. 30. Except when it doesn’t • Spontaneously, heat cannot flow from cold regions to hot regions without external work being performed on the system, which is evident from ordinary experience of refrigeration, for example. In a refrigerator, heat flows from cold to hot, but only when forced by an external agent, a compressor. •This is accomplished by the use of a Refrigeration cycle
  31. 31. Refrigeration cycle Takes advantage of the face that boiling point changes with pressure…and remember that phase change requires/stores lots of energy (latent heat). The Steps of a Refrigeration cycle: (1-2) we boil a refrigerant at low pressure (and so at low temperature too). (2-3) we run it through a compressor to increase the pressure (3-4) then we condense the refrigerant at high pressure (recapturing the latent heat, but at a higher temperature) (4-1) we drop the pressure through an expansion valve and start again
  32. 32. Types of Heat Pumps
  33. 33. Cold Climate Air Source Heat Pumps • Multi Stage • Made by: Inverter Compressor (ductless mini split) – Hallowell (Acadia) • Made by: – Nyle – Mitsubishi – Carrier – Daikin – LG – Fujitsu
  34. 34. Air to Water Heat pump
  35. 35. Ductless Mini Splits • Driving high efficiency and low temperature performance with: – Inverter Driven Variable speed compressor – Scroll Compressors – High efficiency ECM motors – R410 A refrigerant • Single or Multi Split options • Various terminal unit options More than 50% of the air conditioning and heat pump market worldwide is mini splits. In North America is it 2%… …but growing
  36. 36. Single vs multi split • Single Split • Multi Split
  37. 37. Applications • Supplemental Heat • Whole house supplemental heat • Bonus Room heating and cooling • Central Heat Replacement • In new construction • Open concept • What about backup?
  38. 38. Heat Pump Performance: COP • The coefficient of performance or COP of a heat pump is the ratio of the heat supplied divided by the supplied electrical energy. • • • By definition, a resistive electric heater has a COP = 1 Higher COP results in lower electric usage for the same amount of heat generated COP depends on temperature of both source and sink
  39. 39. Mini Split Performance • Low temperature Operation – Heat pump keeps operating down to – 13 deg F including 100% of rated power down to 5 deg F • COP: = 4.1 @ 47 deg F = 2.8 @ 17 deg F =1.7 at -13 deg F …and you get a super efficient air conditioner too
  40. 40. Mini Split Operating cost comparison
  41. 41. Temperature BIN data
  42. 42. Heat Pump Performance: HSPF: Heating Seasonal Performance Factor. (BTU/whr) Effectively an attempt to annualize COP. (HSPF * 0.293 = annual average COP) Must be =/> 8 for Energy Star (tax credit) Must be =/> 10.0 for EM HESP incentive EER: Energy Efficiency Ratio (BTU/whr) Cooling performance at one operating point (95 deg, 80 deg 50% RH) SEER: Seasonal Energy Efficiency Ratio (BTU/whr) An attempt to annualize EER. All new AC > 13 Energy Star > 14 Typical mini split: 20-26
  43. 43. Ecotype reports
  44. 44. Design Considerations • • • • • • • • Sizing Wiring Refrigerant piping Condensate Noise Snow Need for Backup heat? Need for Supplemental heat?
  45. 45. Need for backup heat Depends on system location. Other than extreme cold weather areas, many New England locations no longer need backup with the newest generation of heat pump.
  46. 46. Need for supplemental heat • Heat loss = Heat Gain • With no heat source in a room Heat Gain depends on dT • dT can be uncomfortable
  47. 47. Need for supplemental heat • Heat losses: (15 BTU/hr/deg F) – – – – Ext Walls: 200 sq ft @R40 Ext Windows: 24 sq ft@R7 Ceiling: 160 sq ft at R60 Infiltration: 4 cfm • Heat Gains: (228 BTU/hr/deg F) – – – – Interior Walls: 200 sq ft @ R3 Floor: 160 sq ft @ R3 Air Flow from open door: 100 cfm Internal Gains: ?
  48. 48. Rule of Thumb, from Marc Rosenbaum: “My guideline is that if people will tolerate 4°F lower than the heated space (which in my mind means 72°F heated space, 68°F bedroom) and they leave the doors mostly open, then a point-source heater is viable when the heat loss is 1,000 BTU/hour and the room is occupied; 1,500 BTU/hr is kind of my soft cut-off for considering it. Beyond that, I’ll provide some electric resistance backup in those rooms.” ( Our rule: “Better to have it and not need it, than to need it and not have it. Electric resistance backup heat is cheap, and even cheaper to rough in for”
  49. 49. Converting ‘design day’ loads to annual loads
  50. 50. Converting ‘design day’ loads to annual loads If not in your modeling software, you can estimate it from ‘Design’ load: Annual load (BTU) = ‘Design Load’* 24 * Cd * HDD / (Design Load dT) Where: – ‘Design load’ (BTU/hr) –‘Cd’ = building envelope factor (0.85) – HDD = Heating Degree Days (deg F day) (7,770 for southern Maine) – Design load dT = Temperature difference used in Manual J calcs (deg F)
  51. 51. Discussion/Questions Contact us: Fortunat Mueller (207) 221-6342 Contact us: Fortunat Mueller (207) 221-6342 Professional design, installation and service of renewable energy systems.