How I Built a Zero Carbon Footprint House

How I Built a Zero CarbonFootprint House

Chandu VisweswariahDistinguished Engineer and Senior ManagerTiming and Circuit AnalysisIBM Systems and Technology GroupEast Fishkill, NY, USA

How I built a zero carbon footprint home Do not copy without permission 2 of 37IWECS, Hefei, China, August 2010

SummaryZero carbon footprint house built in May 2009; no oil, gas, propane, coal, nuclear

energy

IBM ResearchYorktown Heights, NY


Outline

1. Geothermal heating, cooling and domestic hot water

2. Photovoltaic solar panels3. Other considerations4. Conclusions Outside the scope of this discussion

Global warming and its effects Energy policy and “dependence on

foreign oil” The frustrations of building a house


Geothermal intuition

Ever been inside a cavein the summer? The cave is cool!

During the winter, that same constant cave temperature is warmer than the air outside

The earth is an abundant source of energy at a constant temperature year-round*

In the winter, ground source heat pumps move heat from the earth into your house; in the summer, they pull heat from your home and discharge it into the ground

*7oC (45oF) to 18oC (75oF) depending on latitude; 12.6oC (53oF) in New York


Winter

Basic idea (one example)

Summer

Hot

pur

on

Col

d pu

ron

Col

d pu

ron

Hot

pur

on

Drawing courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology


Closed vertical loop

6 m (20’) bore spacing (7.5 m (25’) in our case),91 m (300’) deep

Courtesy of Prof. Andrew Chiasson, Oregon Instititute of Technology


Closed horizontal loop



Closed pond loop



Pond loop photos

Copper pipe

HDPE pipe


Open loop

Courtesy popularmechanics.com


How a heat pump works

Low pressureLow boiling point: gas

Accepts latent heatLow temperature

Compressor

High pressureHigh boiling point: liquidGives out latent heatHigh temperature

Expansion valve

Courtesy etccreations.com

Con

dens

or

Eva

pora

tor


Enthalpy curves for refrigerants


System in our basement

Heat pump Heat pump Heat pump

Zone valves

Air handler Heat exchange

coils

To

radi

ant

zone

s


Refrigerant

Direct exchange (DX) 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


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 U.S. 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

*Same boiling point, so cannot be separated by fractional distillation; same composition in liquid and vapor states when distilled or partially evaporated


Puron vs. freonASHRAE 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)

Chlorodifluoromethane

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

*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

Higher pressure, lower mass flow, quieter, 31% higher heat-carrying capacity

For more comparison data, see Appendix


Puron enthalpy curves


Distribution within the house

Forced air works, but radiant is best


Sub-floor radiant


Air source heat pumps

Recent breakthroughs allow operation at low temperatures, but with lower COPs

No wells, no trenches! The face of the future?

Mitsubishi Mr. Slim 26 SEER 9,000 BTU Heat

Pump INVERTER Mini Split System


Outline




foreign oil” The travails of building a house


Average solar irradiance W/m2

Fastest growing source of energy 12,400 MW worldwide by year-end 2007


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!


Stand-offs/mounting


Inverter (in garage)From panels

Dis

conn

ect

Inverter

Privatemeter

To utilitymeter

8,871kWhr

to date


PVWATTS

Performance calculator for grid-connected PV systems http://rredc.nrel.gov/solar/codes_algs/PVWATTS

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)


Type of arrays


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

0

100

200

300

400

500

600

700

800

900

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Solar radiation100Wh/m^2/daykWh fixed

kWh 1D

kWh 2D


Energy vs. tilt and azimuth

Assume 5 kW dc, inverter derating 0.77, NYC

2500

3000

3500

4000

4500

5000

5500

6000

0 (N)

22.5 (NN

E)

45 (NE

)

67.5 (EN

E)

90 (E)

112.5 (ES

E)

135 (SE

)

157.5 (SS

E)

180 (S)

202.5 (SS

W)

225 (SW

)

247.5 (WS

W)

270 (W)

292.5 (WN

W)

315 (NW

)

337.5 (NN

W)

360 (N)

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


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 We have net metering and time-of-day

billing

*Solar south is the angle of the sun at solar noon


Outline






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


Outline






Conclusions We use our geothermal system for heating,

cooling and hot water We use our photovoltaic solar panels for

our electricity needs Net metered, time-of-day billing

Good insulation Energy-efficient bulbs and appliances Our investment will be recovered in ~9

years Technology is available; investment is the issue

We are treading a little softer on this earth Who knows what the future has in store?


Imagine? Floating wind turbines

The first units in production will be 4 kWresidential units that will cost $10,000

Information courtesy of Paul Villarrubia


Energy from photosynthesis?

http://www.popsci.com/technology/article/2010-03/video-artificial-photosynthesis-produces-enough-energy-power-house-one-bottle-water


Thank you!

How I Built a Zero Carbon Footprint House

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