How I Built a Carbon-Neutral House Chandu Visweswariah March 15, 2010 Summary We built a carbon-neutral house in Crotonon-Hudson, NY We have been living in the house since May, 2009 including one tough winter No carbon products involved or burned for our house’s energy needs No oil, no propane, no natural gas, no electricity produced from coal (or nuclear plants) Carbon-neutral house == Carbon-neutral home No compromises on comfort No attempt to construct the house in a sustainable manner/sustainable materials Adds too much to the cost! How I built a carbon-neutral house Do not copy without permission 2 of 56 Agenda and purpose 1. Geothermal heating, cooling and domestic hot water 2. Photovoltaic solar panels 3. Other considerations 4. $$$ (costs, incentives, pay back periods) Outside the scope of this discussion Global warming and its effects Energy policy and “dependence on foreign oil” The travails of building a house How I built a carbon-neutral house Do not copy without permission 3 of 56 The only “political” chart today* How I built a carbon-neutral house *New York Times, 03/14/10 Do not copy without permission 4 of 56 1. Geothermal How I built a carbon-neutral house Do not copy without permission 5 of 56 Intuition Ever been inside a cave in the summer? The cave is cooler than the air outside During the winter, that same constant cave temperature is warmer than the air outside Same principle behind ground source heat pumps (GHPs) In the winter, they move heat from the earth into your house; in the summer, they pull heat from your home and discharge it into the ground How I built a carbon-neutral house Do not copy without permission 6 of 56 Geothermal principles The earth is at a constant 12.6oC (53oF) year-round after about 2 m (6’) of depth* Depends on soil, rocky earth is better Geothermal heating and cooling takes advantage of this abundant reservoir of heat in the winter and “coolness” in the summer We will discuss three main parts Energy exchange with the earth Heat pump and refrigerant Distribution in the house *7oC (45oF) to 18oC (75oF) depending on latitude How I built a carbon-neutral house Do not copy without permission 7 of 56 Winter Summer How I built a carbon-neutral house Hot puron Cold puron Cold puron Hot puron Basic idea (one example) Do not copy without permission Drawing courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology 8 of 56 Energy exchange with the earth Closed loop Vertical loop Horizontal loop Pond loop Open loop With underground water aquifer Energy exchange material Direct exchange (DX): Puron under pressure in copper pipes Indirect exchange: Glycol+water mixture (also called “anti-freeze” or “brine”) in PEX tubing How I built a carbon-neutral house Do not copy without permission 9 of 56 Closed vertical loop 6 m (20’) bore spacing (7.5 m (25’) in our case), 91 m (300’) deep Each well or set of wells used for one zone How I built a carbon-neutral house Do not copy without permission Courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology 10 of 56 Closed horizontal loop How I built a carbon-neutral house Do not copy without permission Courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology 11 of 56 Closed pond loop How I built a carbon-neutral house Do not copy without permission Courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology 12 of 56 Pond loop photos HDPE pipe Copper pipe How I built a carbon-neutral house Do not copy without permission 13 of 56 Open loop How I built a carbon-neutral house Courtesy popularmechanics.com Do not copy without permission 14 of 56 How a heat pump works Low pressure Low boiling point: gas Accepts latent heat Low temperature Condensor Evaporator Compressor High pressure High boiling point: liquid Gives out latent heat High temperature Expansion valve How I built a carbon-neutral house Courtesy etccreations.com Do not copy without permission 15 of 56 How a heat pump works, part 2 How I built a carbon-neutral house Do not copy without permission http://www.dimplex.de/animationen/kreislauf.php?lang=en 16 of 56 How a heat pump works, part 3 How I built a carbon-neutral house Do not copy without permission http://www.dimplex.de/animationen/waermepumpe-passiv.php?lang=en 17 of 56 Domestic hot water Desuperheater In summer, take heat that is extracted from the house to heat hot water Heat water for free! In winter, utilize the same mechanism used to heat water for house heating to heat water for domestic use Reduce water-heating costs by ½ Can also heat water directly by solar power How I built a carbon-neutral house Do not copy without permission 18 of 56 Refrigerant Direct exchange Copper pipes with puron under pressure More efficient Allows for domestic hot water Indirect exchange Glycol + water mixture (also known as “anti-freeze” or “brine”) PEX piping Less efficient How I built a carbon-neutral house Do not copy without permission 19 of 56 Properties of Puron Puron is R-410A, a non-proprietary 50/50 blend of 2 non-chlorinated refrigerants Azeotropic blend* with negligible glide temperature (0.3oF) History 1987 Montreal Protocol 1990 Clean Air Act Amendments R-11 and R-12 (CFCs) phased out 1995 HCFCs have lower ozone-depleting potential R-22 (freon) production stopped Jan 1, 2010, phase-out date for existing units 2030 AlliedSignal/Honeywell invented Genetron AZ-20 (HFC) which was given a generic name R-410A, brand name Puron How I built a carbon-neutral house Do not copy without permission 20 of 56 *Same boiling point, so cannot be separated by fractional distillation; same composition in liquid and vapor states when distilled or partially evaporated Puron vs. freon ASHRAE number R-410A R-22 Type of refrigerant HFC azeotropic mixture of HFC-32 and HFC-125 HCFC Chemical name Difluoromethane (R-32) Pentafluoroethane (R-125) Chlorodifluo romethane Chemical formula CH2F2 (R-32) 50% by mass, CHF2CF3 (R-125) 50% CHClF2 Molecular weight 72.6 86.5 Specific heat of liquid (at 86oF) 0.42 Btu/lb-oF 0.31 Specific heat of vapor at constant pressure CP (at 86oF, 1.0 atm) 0.21 Btu/lb-oF 0.16 Ozone depletion potential (ODP)* 0.00 0.05 Montreal Protocol phase out date None 2030 Higher pressure, lower mass flow, quieter, 31% higher heat-carrying capacity For more comparison data, see Appendix How I built a carbon-neutral house Do not copy without permission 21 of 56 *ODP: a normalized indicator of the ability of a refrigerant to destroy stratospheric ozone molecules referenced to a value of 1.000 for CFC-11 Enthalpy curves for refrigerants How I built a carbon-neutral house Do not copy without permission 22 of 56 Puron enthalpy curves How I built a carbon-neutral house Do not copy without permission 23 of 56 To radiant zones System in our basement Zone valves Air handler Heat exchange coils Heat pump How I built a carbon-neutral house Heat pump Heat pump Do not copy without permission 24 of 56 Winter HP1 HP2 HP3 HP4 HP5 HEC1 HEC2 HEC3 HEC4 HEC5 Tank for house heating/cooling Domestic hot water tank For topping off From well tank Well To house Return Radiant zones How I built a carbon-neutral house Return Air handlers Do not copy without permission 25 of 56 HP2 HP3 HP4 HP5 HEC1 HEC2 HEC3 HEC4 HEC5 Domestic hot water tank Tank for house For topping off heating/cooling From well tank HP1 To house Summer Return Air handlers How I built a carbon-neutral house Do not copy without permission 26 of 56 Distribution within the house Forced air works, but radiant is best How I built a carbon-neutral house Do not copy without permission 27 of 56 Sub-floor radiant How I built a carbon-neutral house Do not copy without permission 28 of 56 Well drilling in “emory” land How I built a carbon-neutral house Do not copy without permission 29 of 56 Air source heat pumps Mitsubishi Mr. Slim 26 SEER 9,000 BTU Heat Pump INVERTER Mini Split System Recent breakthroughs allow operation at low temperatures No wells, no trenches! The face of the future? How I built a carbon-neutral house Do not copy without permission 30 of 56 Agenda and purpose 1. Geothermal heating, cooling and domestic hot water 2. Photovoltaic solar panels 3. Other considerations 4. $$$ (costs, incentives, pay back periods) Outside the scope of this discussion Global warming and its effects Energy policy and “dependence on foreign oil” The travails of building a house How I built a carbon-neutral house Do not copy without permission 31 of 56 Average solar irradiance W/m2 Fastest growing source of energy Do not copy without permission 12,400 MW worldwide by year-end 2007 How I built a carbon-neutral house 32 of 56 Basic physics: light electricity Photons from sunlight hit silicon Some pass through (lower energy), some reflect, some are absorbed (energy > band gap) These create electron/hole pairs Pairs that don’t recombine form a DC current An inverter is used to produce AC current No easy way to store this energy! How I built a carbon-neutral house Do not copy without permission 33 of 56 Ideal conditions South-facing single roof Solar south* is 13o West of South A 9/12 pitch is ideal No chimneys, poles, trees in the way In our case 7.6 KW system 8,100 kWhr per year average Eliminates 14,000 lbs of CO2 per year How I built a carbon-neutral house Do not copy without permission *Solar south is the angle of the sun at solar noon 34 of 56 Stand-offs and mounting How I built a carbon-neutral house Do not copy without permission 35 of 56 Stand-offs How I built a carbon-neutral house Do not copy without permission 36 of 56 Inverter (in garage) From panels Disconnect Inverter How I built a carbon-neutral house Private meter 8,871 kWhr to date To utility meter Do not copy without permission 37 of 56 PVWATTS Performance calculator for grid-connected PV systems http://rredc.nrel.gov/solar/codes_algs/PVWATTS More explanation coming Inputs to the program Location (latitude, longitude, elevation) DC rating of panels (e.g., 5 kW) DC to AC derate factor (e.g., 0.77) Array type (fixed, 1-axis tracking, 2-axis tracking) Array tilt (e.g., 37o for a 9/12 roof) Array azimuth (e.g., 180o for a South facing roof) How I built a carbon-neutral house Do not copy without permission 38 of 56 DC to AC derating factor Component Derate Factors PVWATTS Default Range PV module nameplate DC rating 0.95 0.80 - 1.05 Inverter and Transformer 0.92 0.88 - 0.96 Mismatch 0.98 0.97 - 0.995 Diodes and connections 0.995 0.99 - 0.997 DC wiring 0.98 0.97 - 0.99 AC wiring 0.99 0.98 - 0.993 Soiling 0.95 0.30 - 0.995 System availability 0.98 0.00 - 0.995 Shading 1.00 0.00 - 1.00 Sun-tracking 1.00 0.95 - 1.00 Age 1.00 0.70 - 1.00 Overall DC-to-AC derate factor 0.77 How I built a carbon-neutral house Do not copy without permission 39 of 56 Type of arrays How I built a carbon-neutral house Do not copy without permission 40 of 56 Tilt angle and azimuth Roof Pitch 4/12 Tilt Angle (°) 18.4 5/12 6/12 7/12 22.6 26.6 30.3 8/12 9/12 10/12 11/12 33.7 36.9 39.8 42.5 12/12 45.0 How I built a carbon-neutral house N Azimuth Angle (°) 0 or 360 NE E SE S 45 90 135 180 SW W NW 225 270 315 Heading Do not copy without permission 41 of 56 Energy production by month Assume dc rating=5 kW, inverter derating =0.77, azimuth=180o, pitch=36.9o (9/12), total annual kWh=6,121/7,615/7,840 Solar radiation 100Wh/m^2/day kWh fixed 900 800 700 600 kWh 1D kWh 2D 500 400 300 200 100 0 Jan Feb Mar Apr How I built a carbon-neutral house May Jun Jul Aug Sep Do not copy without permission Oct Nov Dec 42 of 56 Energy vs. tilt and azimuth Assume 5 kW dc, inverter derating 0.77, NYC 6000 5500 4/12 pitch 5/12 pitch 6/12 pitch 7/12 pitch 8/12 pitch 9/12 pitch 10/12 pitch 11/12 pitch 12/12 pitch 5000 4500 4000 3500 3000 2500 43 of 56 360 (N) 337.5 (NNW) 315 (NW) 292.5 (WNW) Do not copy without permission 270 (W) 247.5 (WSW) 225 (SW) 202.5 (SSW) 180 (S) 157.5 (SSE) 135 (SE) 112.5 (ESE) 90 (E) 67.5 (ENE) 45 (NE) 22.5 (NNE) 0 (N) How I built a carbon-neutral house Agenda and purpose 1. Geothermal heating, cooling and domestic hot water 2. Photovoltaic solar panels 3. Other considerations 4. $$$ (costs, incentives, pay back periods) Outside the scope of this discussion Global warming and its effects Energy policy and “dependence on foreign oil” The travails of building a house How I built a carbon-neutral house Do not copy without permission 44 of 56 3. Other considerations Insulation Polar walls R-30 (2x8) Double-fascia roof R-51 Windows Double-pane, low-e argon coating 100% compact fluorescent lamps (CFLs) Think “passage lighting” during design Can now use with dimmers! Transportation alternatives Use bicycles, carpool, hybrids, electric cars, public transportation… “Passive power” reduction/instrumentation Instrumentation is a powerful way to change habits Reduce, recycle, reuse How I built a carbon-neutral house Do not copy without permission 45 of 56 Agenda and purpose 1. Geothermal heating, cooling and domestic hot water 2. Photovoltaic solar panels 3. Other considerations 4. $$$ (costs, incentives, pay back periods) Outside the scope of this discussion Global warming and its effects Energy policy and “dependence on foreign oil” The travails of building a house How I built a carbon-neutral house Do not copy without permission 46 of 56 Rule of thumb for geothermal 1600 sq. ft. requires one 3 ton unit, one 300’ vertical well, and costs ~$10K Add one unit/well for domestic hot water Federal Gov’t will kick back $3K (30%) per heat pump as a tax credit How I built a carbon-neutral house Do not copy without permission 47 of 56 Payback time: geothermal Federal income tax credit of 30% of the cost with no limit till 2016 (undiminished by AMT) For everything up to the heat pump, including labor/install; need to fill form 5695 Requires COP >= 3.5, EER >= 15 for DX systems Different ways of looking at it HVAC system doubles in cost Provides heating at equivalent of $1.25/gallon of oil Additional monthly mortgage cost is less than the monthly energy savings Pays for itself from day one! $1 per year energy savings = $20.73 of house value* Our payback analysis indicates a 9 year payback period We have no backup system for heat, A/C, hot water! How I built a carbon-neutral house Do not copy without permission *R. Nevin and G. Watson, Appraisal Journal, October 1998, pp. 401—409 48 of 56 Insulation, doors, windows Federal income tax credit of 30% of qualified insulation, furnace, doors, windows, storm door and storm window material costs only Capped at $1,500 Must fill form 5695 Must be the first user This is a post-AMT tax credit How I built a carbon-neutral house Do not copy without permission 49 of 56 Payback time: solar panels Solar panel prices are falling! Federal income tax credit of 30% of “system cost” with no limit till 2016 Survives AMT Includes labor, installation Must fill form 5695 See NYSERDA web site at http://www.nyserda.com/ NY prior to 10/13/09: $4/W for the first 5 kW, $3/W for the next 5 kW NY prior to 01/11/10: $2.50/W for the first 4 kW, $1.50/W for the next 4 kW NY now: $1.75/W for the first 5 kW Incentives are higher for EnergyStar labeled homes and Built-in Photovoltaics (BIPVs) Additional $5K tax credit; additional 8.75% property tax credit (now 5%) VT: $1.75/W for the first 5 kW See CA web site at http://www.cpuc.ca.gov/PUC/energy/solar NY state VT state CA state California Solar Initiative: see next page, rebates diminish with popularity On each anniversary of installation, excess generation is paid at “wholesale rate” Utility must buy back excess power at supply cost “Time-of-day” billing is very advantageous for solar customers Payback period in our case is ~9 years How I built a carbon-neutral house Do not copy without permission 50 of 56 California information Expected Performance-Based Buy-Down Performance-Based Incentive How I built a carbon-neutral house Do not copy without permission 51 of 56 Berkeley has special financing How I built a carbon-neutral house Do not copy without permission 52 of 56 LA funds solar by electric premiums How I built a carbon-neutral house Do not copy without permission 53 of 56 Imagine? Floating wind turbines The first units in production will be 4 kW residential units that will cost $10,000 How I built a carbon-neutral house Information courtesy of Paul Villarrubia Do not copy without permission 54 of 56 Energy from photosynthesis? How I built a carbon-neutral house Do not copy without permission http://www.popsci.com/technology/article/2010-03/video-artificial-photosynthesis-produces-enough-energy-power-house-one-bottle-water 55 of 56 Thank you! How I built a carbon-neutral house Do not copy without permission 56 of 56 Appendix Properties of puron vs. freon Basic physics: electricity light How I built a carbon-neutral house Do not copy without permission 57 of 56 Puron vs. freon ASHRAE number R-410A R-22 Type of refrigerant HFC azeotropic mixture of HFC-32 and HFC-125 HCFC Chemical name Difluoromethane (R-32) Pentafluoroethane (R-125) Chlorodifluo romethane Chemical formula CH2F2 (R-32), CHF2CF3 (R-125) CHClF2 Composition (by mass) R-32: 50%, R-125: 50% N/A Molecular weight 72.6 86.5 Boiling point (at 1.0 atm), oF -62.9 -41.4 Freezing point (at 1.0 atm), oF -247 -256 Critical temperature, oF 163 205 Critical pressure, psia 720 722 Saturated liquid density (at 86oF), lb/ft3 64.64 73.09 How I built a carbon-neutral house Do not copy without permission 58 of 56 Puron vs. freon ASHRAE number R-410A R-22 Specific heat of liquid (at 86oF), Btu/lb-oF 0.42 0.31 Specific heat of vapor at constant pressure CP (at 86oF, 1.0 atm), Btu/lb-oF 0.21 0.16 Flammable range (% volume in air) None None ANSI/ASHRAE Standard 34-1992 Safety Group Classification A1 A1 Ozone depletion potential (ODP)* 0.00 0.05 Global warming potential (GWP)**, 100 yr. 1,997 1,780 Montreal Protocol phase out date None 2030 Lower TEWI*** (Total Equivalent Warming Impact) Higher pressure, lower mass flow, quieter, higher efficiency, synthetic lubricants Over 1,000,000 units 1995-2004 *ODP: a normalized indicator of the ability of a refrigerant to destroy stratospheric ozone molecules referenced to a value of 1.000 for CFC-11. How I built average a carbon-neutral house Do not as copy withoutgas permission 59integration of 56 period. **GWP: a mass-weighted indicator of the ability to trap radiant energy a greenhouse relative to carbon dioxide for a 100-year ***TEWI: takes into account direct (refrigerant leaks into the atmosphere: 7.5%) + indirect effects (effects from electricity production used to run system: 92.5%). Basic physics: electricity light How I built a carbon-neutral house Courtesy Wikipedia and HowStuffWorks.com Do not copy without permission 60 of 56