CONTENTS

Facts At A Glance

Introduction

More Detailed Information

Budget
Energy & Environmental Benefits
Economic Benefits
Heating System Summary
Cooling System Summary
Water Heating Summary

List of Energy Saving Features

Insulated to cost-effective levels
Windows face mostly south, capture winter sun
Energy storage materials hold winter heat and summer cool
Refrigerator - small added cost & huge savings
Clothes Washer - super efficient and quite as a mouse
Clothes Dryer - special solar model
Lighting - compact fluorescents make great investment

The picture above was taken on a summer morning. Notice how the trees and overhangs are positioned to shade the windows from the high summer sun. At night, the windows are opened, allowing the inside floors and walls to be cooled by the night air flowing through each room. Every morning the windows are closed, and the house stays comfortably cool as long as the windows remain shaded - exterior sun screen is placed over "exposed" windows that get direct sun certain times of the year.

When backup cooling is needed, a small 2000 CFM evaporative cooler blows cool air into the central stairwell area. At the same time, an exhaust fan pulls the warmest air from the highest point of the ceiling indoors, drawing evaporative cooler air across the living space and forcing it out through the attic. Evaporative cooling is very comfortable in most dry or semi-dry climates as long as the air coming in is exhaused properly. Since relying on "humans" to open windows has not proven practical, the exhaust fan was added. A continuous ridge vent was also added to the attic to augment the existing gable-end vent exhaust openings.

Did you notice the hot water collector on the shed roof at the front of the house? It's a four by ten foot collector and can provide up to 85% of the yearly hot water needs for five people. Backup water heating is provided either by an electric element in the solar storage tank or a fifty gallon propane-gas water heater with an Energy Factor of 0.62. A similar, though much improved, system like this called the "High Sierra Drainback" system is available from Morley Manufacturing, Grass Valley, California (916-274-2609 or 477-6527).

Maintenance for the solar hot water system involves turning the cold water supply valve until the water level marker on the side of the tank rises to between the markings. It's similar to checking the oil level in your cars engine, only much easier, and only needs to be done twice a year. Otherwise, the only other maintenance is flushing the solar tank when the backup water heater is flushed, about every two to three years due to extremely good water quality. Note: a regular gas or electric water heater can last two or three times longer than usual if it's flushed regularly of sediment.. In terms of replacement of components, the pump, the pipe insulation exposed to weather, and the collector sensor were replaced in 1993 (after 10 years of operation) at a cost of approximately $300.

* Building or energy design costs were zero; owner-builder provided these services.

THE MANY BENEFITS OF A MORE SUSTAINABLE HOME DESIGN

A comparison of this homes energy costs with a brand new home (built to current energy standards) is shown in the chart on the left. On the average, the Darby's energy bill totals $731/yr ($61/month) which, compared to a new home at $1642/yr ($137/month), saves them $912/year ($76/month).

Overall, the energy measures reduce the energy use of this home by about 55% relative to a new home! This is noteworthy for a low-budget remodel/addition to a 1974 vintage home.

More Sustainable Electricity Is Used -

Renewable energy is made from natural sources, like wind or solar, that will last indefinately. This is a more sustainable approach than using fuel-powered electric generators that burn coal, oil or natural gas. Fossil fuels are finite, or "non-renewable" sources of energy. And on top of that, about one third of the energy generated at a power plant is lost over long distance transmission line and distribution (T&D) systems.

A renewable generator at your home, on the other hand, loses only a few percent of the energy you generate before you use it, making it far more efficient than a (central) power plant system. The more people begin making their own power - referred to as "distributed generation" - the less likely it will be you'll have a high voltage transmission line in your backyard's future.

We need to be aware of the fact that the big utilities, accustomed to building central power plants, are calling on our government to build a huge new interstate T&D system. This will require considerably more public investment than distributed generation, especially in the long run. The T&D system will necessitate taking over peoples land to significantly expand our interstate transmission line system, which will be difficult and costly due to population growth - no one wants high voltage lines in their backyard and easements will be expensive. Then there's the cost of designing this huge T&D system, plus the cost to build and maintain it. Any guess as to why the big utilities are all pushing the Federal Government to invest in T&D instead of distributed generation?

This home uses an optimum mix of renewable energy resources for electricity generation. A micro-hydro power system, poweredby two seasonal springs, is used to generate up to 12 kWhrs/day of the home's power during the winter months. A 2.4 kW PV (photovoltaic) solar power system can provide up to 11 kWhrs/day during the summer months (an average home uses about 15 kWhrs/day). Most of the energy used to power this home - or the family's electric vehicle - comes from renewable energy.

As an added bonus, the local utility (on a very limited basis) has made Time Of Use (TOU) meters available to a small number of residential customers. With a TOU meter, we can essentially purchase all of our electricity during off-peak periods (summer nights) at about 4 cents/kWhr, and sell electricity during peak periods (summer days) at about 31.5 cents/kWhr. In winter, the rate is 10 cents/kWhr during partial-peak and 5 cents/kWhr off-peak (nights and weekends). The cost of electricity for the home AND electric vehicle (which accumulates over 15,000 miles/yr) is free when electricity use is minimized during peak solar (and rate) hours, batteries power the home during peak rate periods when the sun isn't shining, and the EV is charged off-peak.

Given the combination of California's renewable energy buydown program, net metering, and TOU rate schedules, the economics of renewable electricity has become extremely attractive. Our electricity bill now includes just basic service charges - about $10/month. This is because every excess kWhr that runs the meter backwards during peak in summer buys about seven kWhrs during the off-peak period (a "seven for one" deal). In winter, it's a "two for one" deal. Net metering customers receive a "true-up" statement once a year, showing the net bill (or credit) for the year. Unfortunately, you cannot get a check at the end of the year if you've built up a credit - your account is simply zeroed out in that case.

On-site production of green power also helps increase the installed base of renewable power generation, eases the need for building new expensive new power plants, expensive T&D infrastructure, and helps to add just a little bit more reliability to California's electric grid at a time when California really need it! Furthermore, considering the serious challenges we face with global warming, a home that lessons the impacts of (and need for) fossil-fueled power is helping to address the problem rather than add to it.

Less Pollution from Gas Use -
Normally, a family this size dumps about 3000 pounds of CO2 - the main global warming gas - into the air each year, just from water heating alone. That's a couple pickup loads worth a year! The solar water heating system in this house reduces that pollution by 60-100%, depending on the season and the fuel choosen for water heating when the sun doesn't shine (either gas, electric, or both can be used as backup).

Clothes drying is done with a solar dryer (a clothes line) whenever the conditions permit, and an outdoor solar oven from Solar Cookbox International is sometimes used for cooking to help keep the indoors cool in the summer.

All of these things help to reduce pollution, as well as contribute to a more sustainable use of energy.

ECONOMIC BENEFITS
Note: The benefits below are for the home itself, excluding the renewable electricity systems. Refer to the power system links, above, for the renewable power generation system benefits.

* Stamped concrete floor cost approximately $880 less than the least expensive carpet & pad

* Evaporative cooler saved an estimated $500 over an air conditioner of similar capacity

* Ridge vent cost approximately $2.00/ft (installed) for a total of $118

* Active solar hot water system cost $1,500 in 1983, given the 50% tax credit available at the time.

* Installed cost of radiant floor heating system, including water heater, was approximately $2500, a savings of approximately $500 when compared to a 78% eff. gas forced air heating system.

* Double sheet rock was necessary to cover up original wood paneling (which was glued to sheet rock) and was needed for aesthetics, therefore no added cost is assumed.

* Phase change storage cost approximately $350 (no longer available).

* Tiled showers and entry floor was done by owner-builders for no added cost relative to fiberglass/vinyl.

* Sunscreen cost was $60.

* Fluorescent lighting cost $380 more than incandescent lighting (a total of 23 bulbs at $16.50 more per socket over 10 years).

* Total (net) added cost of energy features $ 800

* In simple terms, the $800 net added cost of the energy features are recovered after approximately two years of $455/yr savings. Subsequent year savings of $455/yr are equivalent to "interest income" (taxes, inflation and other factors included). Thus the extra $800 we "invested" in energy features ten years ago, with an annual "interest return" of $455/yr, gives us a "return on investment" of over 200%, one hundred times more than a 2% passbook savings account offers - or most any other investment, for that matter, since this "interest income" is tax free!

SPACE HEATING SUMMARY
* 23% less heating energy consumption than new home built to 1995 California Energy Standards.

* South windows allow winter sun to enter and absorb into the interior mass of the home.

Backup heating system:
* Unlike many Sierra Foothill homes, this home has no wood stove (due to air quality and living space considerations)
* 85% recovery efficiency, 50 gallon water heater heats home and hot water
* Majority of home heated by hydronic radiant floor under raised wood floor and within slab on grade
* Small catalytic propane radiant wall heater = 85% efficient heats entry area
* Hot water baseboard heater heats stairwell and a portion of the living area
* Heat distribution pumps and wall heater powered by 12 volt D.C. system; eight 12 volt (220 amp-hr) batteries allow up to a week of space heating in the event of a power failure.
* Comfortable, low-cost, simple, quiet, low maintenance and energy efficient design


SPACE COOLING SUMMARY
* 84% less cooling energy consumption than home built to 1995 California Energy Standards.
* Summer cooling through night ventilation & sun control
* Natural night ventilation cooling with high & low windows opened
* Optional forced night cooling using "vent only" mode of evaporative cooler
* Ridge vent + gable end vents for attic ventilation (radiant barrier not yet installed)
* Deciduous and non-deciduous trees provide summer shade on East, West, and North
* Shade screen applied to windows not shaded by trees late spring, removed late fall
* Overhangs and trees (see views below) shade house in summer from the east sun in morning and the west sun in the afternoon -

* Backup cooling system: a 2000 CFM direct evaporative cooler


HOT WATER HEATING SUMMARY
* 85% of domestic hot water heating provided by solar energy (measured) with electric auxiliary; 65% estimated solar fraction using gas auxiliary (system allows gas and/or electric backup).

* Drainback-Thermosiphoning type active solar domestic hot water system (1983 Trident Thermosiphon Storage to 50 gallon electric water heater).

* Auxiliary heat source: 85% recovery efficiency, 0.62 Energy Factor, 50 gallon hot water heater.

Insulation
* Walls: R-19 (within all new & replaced walls); R-11 original walls

* Ceiling with attic: R-40 (R-21 cellulose fill over R-19 fiberglass)

* Vaulted roof: R-36 (4 1/2" polyisocyanurate foam @ R-8/inch)

* Raised floor: R-19 floor over crawl

* Slab edge: R-10 (2" extruded polystyrene @ R-5/inch) perimeter slab insulation to 24" depth with termite shield and termicide treatment of adjacent ground; earth berm to within 6" of slab top to reduce heat loss and help protect slab edge insulation.
glass
* Windows: Simonton Vinyl frame, double pane low-e units on all south and double pane double-low-e glazed units on all non-south glass.; U-value=0.35 to 0.38. Note: these windows were added since the last analysis of energy use; the savings discussed above do not yet reflect the change to these windows (from Milguard, Metal Frame, Double glass, U=0.75).

Windows positioned with the path of the sun
Almost half the windows in the home face south, allowing more natural sunlight and heat into the home in winter than an average home. Trees surrounding the home on the north, east, and west have been carefully trimmed to allow the low (in the sky) winter sun to shine brightly on the south facing windows.

In summer, these same trees form an "umbrella" of shade from the high (in the sky) summer sun. Most windows are shaded by trees, with the remainder shaded by interior shades, exterior sunscreen, or some combination. Window areas, by orientation, are:

South = 144 square feet (8.2% floor area)
East = 81 sf (4.6%)
North = 6 sf (0.3%)
West = 70 sf (4%)

East facing skylight = 7.5 sf

Total window area = 309 sf (or 18% of the floor area).

Energy storage materials to hold winter heat and summer cool
Energy storage materials are used to capture and hold the heat of the sun in winter, and the "coolth" of the cool night air in summer. Energy storage materials distributed throughout home include:

* Stamped concrete slab downstairs (520 s.f.) which looks like 8" x 8" slate-colored "tiles".
* Five foot high, 8" thick retaining wall at north, tapering down to ground level at south.
* Double sheet rock (one inch) throughout most of upstairs interior and exterior walls (583 s.f.).
* Ceramic tile used in both bathroom shower surrounds, vanities, and on entry floor.
* Phase-change heat storage "sandwiched" between radiant heat panels (below) and 3/4" plywood subfloor (above) in dining room; 3/4" thick phase change packets provide heat storage capacity equivalent to approximately 6" of concrete. Note: these are no longer commercially available.

Refrigerator/freezer
* Whirlpool Model ET18HT
* 551 kWh/year (new models range from 518 to 697 for this size refrigerator).
* Costs $66/year (new models range from $62 to $83/yr).

Clothes washer
* Maytag Neptune washer saves up to $100/year in electricity and gas costs.

Clothes dryer
* A solar dryer (clothes line) is used approximately half the year. It is attached to an old hook embedded in an old Grandfather Oak tree (below). The tree is 208 inches in diameter (DBH), five and a half feet in diameter, over 200 years old, completely hollow (two people could climb through to the top, side by side), and still very much alive (click on the image for a larger view)! Our other (automatic) clothes dryer has auto-moisture-sensing, shutting off automatically to save gas and electricity when the clothes are dry.

Compact fluorescent lights
* Various types of compact fluorescents were added over time to virtually all fixture types.
* Lighting costs are approximately 1/3 those of incandescent bulbs for equivalent lighting.