Build Solar

7/21/2019 Build Solar

http://slidepdf.com/reader/full/build-solar 1/54

This house was built "underground," usingthe earth for shelter from the elements, andit also uses passive solar features to pro-vide much of its heating requirement.

The site is well suited for an earth-sheltered, passive solar house. Located ina custom home subdivision, the 4-acre siteis on the south side of a 10percent gradethat also slopes off to both east and westfor good drainage. A stand of pine trees,

along with a higher hill to the northwest, af-fords protection from the prevailing north-west winter winds.

To augment the collection of solar energy,the house is built on two levels, with thenorth half higher than the south half. Thisdivision permits a row of south-facingclerestory windows for the northern rooms.Sunlight is collected through these and adouble band of south windows and through



Along the house perimeter, a 1-inch foam-board (R-5) is installed across the face of the first-floor slab and turns under the slabfor 2 feet. Finally, all cracks around win-dows, doors, and exterior corners are hand-chinked prior to insulation to minimize air infiltration into the building envelope.



the greenhouse, which is on the lower leveland in front of the living room. While part of the solar energy warms all of the roomsdirectly, much of it is absorbed and stored

in the house's internal masonry. The in-terior north walls of all rooms are stuccoed12-inch cored concrete block. The roof isstuccoed 8-inch to 12-inch precast concretewith additional 2-inch concrete topping.This absorbs solar heat that collects in therooms by day and is able to store most of it

because it is underground, not exposed tothe elements. The exposed concrete floor slab of the greenhouse also absorbs andstores solar energy. Heat is distributedfrom the greenhouse into the living roomby convection when the sliding door isopened. There is also a continuous register in the greenhouse ceiling that opens intothe hollow cores of the concrete plank roof.Since the cores of the plank run toward acontinuous vent on the north rooms (about4feet above floor level), heat also flowsdirectly from the greenhouse to theserooms.

At night, heat is distributed as it radiatesout from the walls and ceiling to warm therooms. While the greenhouse register andsliding door are closed to isolate it from thehouse, radiant heat from its floor and wallskeeps it warm enough to act as a buffer for the living room. Additional radiant heat canbe provided by the centrally located woodstove.

Windows, as well as the sliding glass door at the greenhouse, are double glazed andheat loss through them at night is con-

trolled by roll-down interior insulatingshades (R-15).The louvers at the clerestorycan also be covered at night with moveableinsulating panels to control heat loss. Glaz-ing for the greenhouse consists of twolayers of Teflon® film sandwiched betweentwo layers of crystal glass (R-4). Both en-trances are separated from living spaces byair-lock vestibules.

The two roofs overhang the south-facingglazing at both levels to shade the windows

65



from summer sun. Vines are planted at theoverhangs and a vine-covered trellis is lo-cated at the main entrance in front of thewindows. These vines extend the windowshading into late summer and early fall toprevent overheating. As solar heating is re-quired, they are trimmed back.

An aluminum slat shade is extended over the greenhouse in summer while ventilationis induced by opening the vents located inthe east and west walls; the ventilation is

aided by a thermostatically controlled fan.In the main part of the house, a 6-inch

diameter buried tube that tempers combus-tion air for the wood stove in winter alsoprovides low-humidity, earth-cooled air inthe summer to both levels of the house.Warm air in the house is absorbed in thethermal mass walls and roofs from where itis absorbed by the earth, which has a near-ly constant temperature for natural cooling.

Also, any excess warm air is exhaustedthrough fixed louvers in the clerestory bythe effects of natural heat rise.

The passive features of the house areaugmented by the conservation features of

the earth-sheltered design. With 80 percentof the roof and wall surfaces covered withearth, insulation value is inherent. In addi-tion, effects of prolonged cold or warmspells are delayed up to a week, by whichtime conditions should moderate.

The concrete roof planks with interior stuc-co and exterior 2-inch concrete are toppedby 5 inches of polystyrene insulation, 4 in-ches of stone, and a minimum of 14 inchesof earth for a total average thermal value of

R-31.The earth is planted with crown vetchto provide a thick protective ground cover



which will shade the earth and provideevaporative cooling in the summer. Wallconstruction is solid concrete block withvarying widths of pOlystyrene insulation ap-plied to the outside of the wall. There is 5-inch insulation down to 8 feet; below thatthere is 1 inch of insulation. The insulationis covered by a special cement waterproof-ing. The average wall thermal value is R-23.The exposed south wall has 4-inch poly-styrene over block, with stucco finish onboth sides (R-23).At the clerestory level,

construction is 2- x 6-inch wood frame with

full fiberglass batts (R-22). Floors are leftuninsulated, except within 3 feet of thesouth face of the house, to permit the earthmass in contact with it ,to reach room tem-perature and serve as a storage area tohold excess heat and moderate the roomtemperature.



All houses built in Davis, California, mustconform to the city's energy-conservationordinance. This traditional ranch house hasbeen built almost to the book to meet theserequirements.

Its compact form, with a heated area of 1180square feet, avoids a box-like appearance bythe use of protruding side wings for the twobedrooms, a gently sloping roof to deflect thenorth wind, and a separate carport and shopwing attached by a breezeway.

Windows on the east and west sides havebeen kept to a minimum; cross-ventilationhas been emphasized to take advantage ofthe Sacramento delta winds; double glazinghas been used throughout; and overhangsand trellises are included to protect thehouse from direct sun. The house is oriented10 degrees east of true south.

Serving as collectors are three standard,double-glazed aluminum greenhouses in-corporated into the south side of thehouse. Fin walls jutting out to the level of



the entrance form "pockets" for the green-houses. The center foyer opens on eitherside to the greenhouses.

On the east and west flanks of the house, twobedroom wings extend with sliding glassdoors facing south to act as additionalpassive collectors. Opening onto trellis-covered patios, these allow some winter sunexposure for the bedrooms and excellentcross-ventilation in the summer.

Absorbing and storing solar radiation arebrick floors in the greenhouses that are set insand on 4-inch thick concrete slabs, andthree black-painted steel water tanks, 2 feethigh, dividing each greenhouse from the liv-ing room, dining room, and kitchen. The tanksare built in under functional counter tops withsliding glass windows closing off thegreenhouses from the rest of thehouse.

On winter nights, stored heat is distributedby radiation from the tanks directly to therooms and an insulating curtain is drawn toprevent back losses from the tanks to thegreenhouses. A convective distribution is setup between the greenhouses and theremainder of the living area by opening thesliding glass windows over the three watertanks.

The amount of solar energy admitted to thehouse can be controlled by the raising orlowering by crank of three outside syntheticcanvas (acrylic) blinds which are installedover the glass contours of the greenhouse.

A wood stove, centrally located in the livingarea, provides back-up heat.

On summer days, the adjustable sunshadeis lowered, the tank insulating curtain ispulled down, the skylight shutters areclosed, and the hatches to the attic and thevent-louvers to the garden are opened toallow cross-ventilation of the greenhouse. Inthe cool of the evening, moveable insulationis raised, and all hatches and vents openedto allow natural cooling. In the event that

there are no breezes, an exhaust193



fan with a manually timed switch ventilatesthe house. The year-round climate in Davis ismild. Extreme summer heat can be takencare of by one air conditioning unit in thewest wall of the living room.

An active solar domestic water heatingsystem also provides an effective spaceheating back-up in winter. Hot water ispumped through fan-coil units andbaseboards using, in the process, relatively

little mechanical power.

The house could be considered a model forthe energy-efficient requirements of thecity of Davis. It has R-19 insulation in thewalls and R-30 in the roof, double glazing,insulated and shuttered skylights, and win-dows and doors that are all caulked andweatherstripped. The R-6 perimeter insulationminimizes slab edge losses. The use ofunnecessary glass has been avoided andwindows facing east and west kept to aminimum to prevent summer overheating.

A storage room, a carport, and a shop form aseparate wing of the house and are con-nected by a trellis-covered breezeway. Thisnorth-facing service area deflects northwinds from bedrooms and bathrooms. Therepetition of the trellis motif, along the southfront and over the east and west south-facingpatios, give the house an airy appearanceand is another pleasing element of a housewell designed in many ways.



This contemporary house has beende-signed to compete in a very active spec-ulative home market; the approach hasbeen, therefore, to work largely withinexisting construction methods andmaterials to arrive at a design that is bothenergy efficient and economical. The lot onwhich this 2-story, wood-frame home isbuilt slopes from north to south, affording itmaximum exposure to the sun's path

across the southern sky. Tall deciduoustrees to the southwest havebeen leftstanding to deflect winter winds.

Collection of solar heat by the greenhouseat the southeast corner of the house occursthrough four double-glazed sliding doors,and through a pair of Kaiwall skylights(also double glazed) on the pitched roof. Avertical Kaiwall collector is used to heatwater tubes just west of the front entrance. Another pair of sliding glass doors collects

direct solar radiation for storage in thelower-level master bedroom. Roof-mounted,active flat-plate collectors are used topreheat domestic water.

Solar radiation is absorbed and stored inthe greenhouse by eight Kalwall water tubes, and the 15/8-inchbrick pavers of the

floor.

Separating the lower greenhouse from theliving and dining room behind it is a pair of sliding glass doors that allow solar heat intothese areas. Water tubes are also used toabsorb and store heat in the "solar bat-tery " within the central staircase. Threemore water tubes absorb and store heat in

the master bedroom.

Distribution of heat is accomplished byradiation from storage masses as well asnatural and forced convection. Heat that



gathers near the greenhouse ceiling caneither flow into upper-levelliving areasthrough a window andvents, or be drawn inby athermostatically controlled through-wall fan. Heat from the water wall on the

other side of the front entrance is dis-tributed by aconvective loop that pullscool floor air into the water wall throughvents, so that it can be heated and risethrough hinged damper grilles at the top of the stairwell. Fromthere it rises to theupper level. Another natural convective loopis set up when bedroom doors are left openso that the heated air can pass throughnorth wall floor vents as it cools and losesbuoyancy. At night when storage masses

are supplying heat, a fan draws warm air that has risen to the ceiling of the utilityarea at the top of the stairs through a ventto the heat pump air handler. From there itis distributed to all rooms through ducts

and floor registers. The master bedroom,too, is included in this network. When heatfrom storage masses is insufficient to meetthe demands of the thermostat, the heatpump will turn on to make up the dif-ference. The woodburning stove can befired up to restrict use of the heat pump.

During summer, the storage masses areshaded by retractable awnings over allsouthern apertures. Heat that does gather

in the greenhouses can be vented by open-ing ducts that connect to three 14-inch tur-bine fans on the roof. The turbines can beused to vent the entire house by openingthe doors and windows to the greenhouse.

Cross-ventilation is set up by opening eastand north bedroom windows. A central air conditioning system also uses the centralduct system.

Extensive caulking and weatherstripping,and a 6-mil vapor barrier throughout the en-tire energy envelope help to reduce infiltra-tion. Floor insulation over the crawl spaceis rated at R-19,walls are R-11,and theroof is R-30.

73



The site of this project is a portion of va-cant pasture on a gentle south-facing slope.The architect, recognizing the energy-conservation potential in landscaping, hascombined plantings and earth berming toprotect this rustic contemporary home fromwinter winds. The 5-foot high earth berms,located on the west, east, and north walls,also provide a thermal lag for reducing tem-peratures during the hot Georgia summer.

The evergreens planted to the northwestside deflect and diffuse the coldest of winter winds. Together, the earth bermsand plantings create a pleasing entrancefrom the street side and a private rear yard.

The style, floor plan, and siting of thishouse place strong emphasis on market ap-peal and demonstrate that tradition can mixwell with passive design. The 2-story floor plan is one that has had great success in

the area. The overall·design follows a linethat has been well accepted by Atlanta areahome buyers.

This house is notable for the innovativepassive heating approaches that provide amajor part of its energy needs. Three pas-sive collection types are used: (1) over 100square feet of south-facing double glasscollects heat for all of the major living andsleeping spaces except the kitchen; (2)nearly 300square feet of double-glazedTrombe wall fill the entire balance of thissouth wall, providing long-term storage; (3)an isolated system is formed by approx-imately 200square feet of single glazingthat covers a portion of the south-slopingroof.

Absorbers include three major surfaceareas, two of which are black-painted con-



crete walls. The other is blackened metalplates installed below the glazed part of thesouth roof.

Storage for the direct radiation is a massiveconcrete slab floor, as well as 8-inch con-crete block perimeter walls with exterior insulation. The Trombe wall uses 12-jnchconcrete-filled blocks to store heat for later use. Heat from the roof collector is storedin a 500-cubicfoot rock storage area belowthe livi ng room and master bedroom floors.

Radiation and natural convection distributeheat throughout the livi ng spaces. The rockstorage bin also radiates heat, but theseflows are delayed and continue for manyhours after sunset. They provide heat for the living spaces during cloudy and night-time periods. Natural convection occursboth within rooms and throughout thewhole house.

A strong convection loop is established inthe winter when the Trombe wall is being

charged with solar energy. The air in thispartially closed loop leaves the bottom of the rock storage, is heated and as it rises,passes between the glass cover andblackened masonry of the Trombe wall. It isthen further heated as it turns and rises upthe face of the site-built roof collector. Thisair is then ducted past a domestic water preheat tank to a high pOint in the roof where a fan draws it down into the rockstorage area below the living and bedroom



floors. From there it directly heats the roomabove.

This house makes use of a number of control features that respond to outsideclimatic fluctuations in order to maintain in-side comfort. The roof overhang and fixedlouvers shade the southern glass andTrombe walls from April until September.Polyethylene-faced backdraft dampersautomatically prevent reverse thermo-siphoning of the Trombe walls, and the

solar roof permits these devices to bevented to assist interior air circulation dur-ing periods when heating is unnecessary. Adecorative living room fan helps to elimi-nate air stratification by forcing warm air atthe ceiling back down into the room.

Back-up heating is provided by a fireplaceand a small gas-fired forced-air systemactivated by a clock thermostat. A conven-tional cooling system sharing the heatingunit's fan and duct system provides back-up air conditioning. A gas-fired water heater tank supplies the balance of the domestic

hot water needs. All back-up systems,including the fireplace, water heater, andfurnace, receive their combustion air direct-ly from the outside, rather than wastealready heated inside air.

Walls not shielded by earth berms have 6-inch studs sheathed with 1-inch rigid insula-tion. The roof is insulated with 12-inchfiberglass batts. The floor slab is poured on1 inch of rigid insulation. The building iscarefully zoned with garage, service, andstorage areas on the north side. The en-trance is a well-planned, naturally lit air-lock

vestibule.

This Roswell, Georgia, house effectivelycombines outstanding passive design witha popular style to achieve both energy effi-ciency and great marketability.

79



––

Builder: Starbird Lumber Co., Strong, ME

Designer: Sunsystems, Dryden, ME Solar

Designer: Sunsystems

Price: $55,000 to $60,000

Net Heated Area: 1204 ft^2

Heat Load: 65.8 x 10^6 BTU / yr

Degree Days: 8675

Solar Fraction: 71 %

Auxiliary Heat: 1.82 BTU / DD/ ft^2,

Passive Heating System(s): Direct gain, indirectgain

Recognition Factors: Collector(s): Triple-glazedwindows, double glazing over Trombe wall, 418 ft^2 Absorber(s): Trombe wall surface, concrete floorStorage: 8-inch concrete floor slab, concreteTrombe wall capacity: 37,617 BTU /F Distribution:Radiation, convection Controls:Vents, shutters; differential thermostat forforced-air system

Back-up: Wood furnace

Passive Cooling Type: Cross-ventilation, solarchimney through Trombe wall, mechanical cooling

18

This saltbox-style home, updated to makethe most of solar energy, is located on agentle south-southeast slope. A band of tallhardwood trees along the lot's western endprotects the home from prevailing winterwinds. The rest of the lot is covered withyoung red pine trees, except where theywould shade passive collection.

The compact saltbox layout allows the hometo enclose a large amount of interior spacewith a minimum of exterior wall surface. Thisis an important part of the overallconservation package. There are 6 inches offiberglass insulation in the walls and 12inches in the ceiling. Closets and other low-use areas of the home are located alongthe north wall; the entryway is sheltered by arecess and by a vestibule.

Except for the south-facing solar collectionwall, the entire lower floor of this home is

buried. This moderates the inside tempera-ture by exposing the outside surface of thelower-floor walls to the temperature of .theearth below the frost line, rather than thesubfreezing temperatures of a Maine winter.

During the summer, this helps cool the homebecause ground temperature stays wellbelow summer air temperatures.

This home is heated by two types of passivesolar energy collection: direct heatingthrough windows and a Trombe wall system.

The direct collection relies on a total of 186square feet of south-facing windows and 26square feet total of east- and west-facingwindows. All windows are triple glazed.

During the day, sunlight passes through tne

windows and strikes the 4-inch concrete slabfloor and the cored concrete block in-



terior walls. These surfaces function assolar absorbers, turning the sunlight intoheat. The heat is conducted into the interiormass of the floor and walls, where it isstored.

At night, when the air temperature in theliving space drops below the temperature ofthe storage walls and floor, heat from thestorage mass is distributed to the livingspace by radiation and convection.

The system has two types of controls. Theinsulating panels are used to cover the win-dows at night to reduce heat loss to theoutside, and they are used on particularlysunny spring and fall days to limit heat gain.White shades are drawn over the windowsduring summer days to reflect direct sunlight.

If the upper-floor temperature is greater thanthe lower-floor temperature by apredetermined amount, the second control

system is called upon. A differentialthermostat turns on a small blower whichforces the warmer air through a concreteblock interior storage wall, and then outthrough floor vents on the lower level. Thisprocess evens out the temperature of thehome by storing some of the upper floor'sheat in the block wall, and by circulating therest of it to the lower floor. The blower can beoperated manually as well as automatically.

The Trombe wall consists of a concrete-filled block wall with a black painted exterior

surface. A double-glazed window isattached 6 inches in front of the exteriorsurface. During the day, sunlight is col-lected as it passes through the glazing.It strikes the blacK. surface of the wall,where it is absorbed and then stored in thesolid mass wall. It takes hours for the heat topass through the wall, finally reaching theliving space after sunset. This delay savesthe sun's heat for distribution as radiant andconvective heat from the wall at night.



21



South-facing collectors have been provided forall major living areas of this 3-bedroom solardesign. Each of the two upper-level bedrooms

has four windows for heating individual storagemasses, while the firstfloor master bedroomhas three windows and no storage. There arethree sliding glass doors collecting heat in thedining room. The family room, located betweenthe dining room and master bedroom, haseight vertical glass collectors and a sloping roofmade entirely of Kalwall Sunwall panels. Thesepanels have an R-value of 4.1, which isincreased to R-10 with the use of integratedroll-out window quilts at night. All windows aredouble glazed and have fixed overhangs.

In the family room, there are two surfacescapable of absorbing and storing a significant

amount of heat: an 8-inch concrete slab floorcovered with brick pavers, and the 8-inchmasonry wall at the north end of the room.The dining room has only the brick-coveredslab floor. In the upstairs bedroom there arelarge brick-covered window sills absorbingheat for the 6-inch concrete storage slabbeneath.

Backing up these solar systems in the winterand at night are a woodburning stove (withinthe masonry wall of the family room) and agas furnace. The furnace is equipped with an

air handler that can operate independently ofthe heater to evenly



distribute heat radiated from storage masses.This is accomplished by the return air intakein the ridge above the familyroom where heated air, which gathers thereby natural convection, is drawn down into thefurnace by the air handler and supplied to therest of the house through floor and wallregisters. Because the stove's flue closelyparallels this air intake tube within thechimney, use of the stove will significantlyraise the temperature of air being drawn

down for distribution. As the stove draws itscombustion air from the outside, its use willnot diminish internal pressure. Duringextreme cold, the gas heater will activateautomatically until the thermostat is satisfied.Heat loss at night is controlled by the windowquilts that cover the Kaiwall panels, slidinginsulation panels on the upper-level bedroomwindows, and conventional draperies on allother vertical glass.

In summer, when the temperature in thefamily room rises above l8°F, a thermostat

will open a motorized damper in the ridgeto exhaust hot air. The damper also opensif the outside thermostat indicates outsidetemperature to be about 68°F. To aid in ven-tilation, there is a manually opened electricfan box within the plenum with intake ventsalong the top of the skylight. When the win-dow quilts are drawn to prevent solar gain,there is an air space left between them andthe glazing. The fan draws the hot air outfrom this space, which in turn draws coolerair in from vents at the bottom of the glazing.Overheating is further controlled by

use of the same moveable insulation anddraperies used to control heat loss.

Earth berming has been used on all sides tohelp stabilize interior temperature. To reducewind infiltration, buffer spaces (closets, utilityspaces, etc.) have been located along thenorth wall of the house; the garage on thenorthwest side protects against prevailingnorthwest winds. Attic insulation is R-38, andwalls are R-19.



Builder: Bonnerville Construction Corporation,Monsey, NY

Designer: Perillo Associates, Hawthorne, NY Solar

Designer: Perillo Associates

Price: $125,000

Net Heated Area: 2550 ft^2 Heat

Load: 146.0 x 10^6 BTU/yr

Degree Days: 4862

Solar Fraction: 38%

Auxiliary Heat: 7.34 BTU/DD/ft^2

Passive Heating System(s): Direct gain, isolated gain,sun~tempering

Recognition Factors: Collector(s): South-facing windows,greenhouse glazing, 466 ft^2 Absorber(s): Block wall,concrete floor surface Storage: Block wall, concretefloor-capacity: 12,230 BTU / 0F Distribution: Rad iation,natural and forced convection Controls:Moveable insula-tion in greenhouse, shutters, registers, vents, trellis

Active Solar Heating: See DHW

Back-up: Furnace (88,000 BTU / H)

Domestic Hot Water: Liquid flat-plate collectors (105ft^2)

54

Rockland County, New York, has unusually highutility and fuel rates, second only to the nation's

highest in New York City. This fact was a majorconsideration for the builder when he plannedthis center hall, contemporary passive solarhouse. As a result, he has kept to a minimum theenergy consumption of the house's simpleauxiliary heating system.

The house is currently the only passive solarhouse in a growing subdivision where marketdemand has been for large residences withclearly designated living areas. However, itsdesign is sufficiently inconsp~cuous to let it

blend in with more traditional homes in theneighborhood.

Two greenhouses flanking the front approach onthe south side act as passive solar collectors for

heating the dining room and living room. Inaddition, five clerestory windows over the 2-storyliving room and three pairs of windows in the twosouth-facing bedrooms upstairs act as collectors.

Each greenhouse has a 6-inch concrete slab floorcovering a total of 466 square feet. The radiationis absorbed and stored in a solid 12-inch concrete

block wall with black painted textured surfacesfacing south. A 6-foot sliding glass door islocated in each storage wall in the greenhouses,allowing the sun to directly enter thehouse, and in the case of the living room



on the west side, strike the 4_inch solidconcrete slab floor for additional heatstorage.

Heat is distributed into the living and diningrooms from the two greenhouses by radiation andthen natural convection conveys the heated airthrough high registers into upstairs bedrooms. Atwo-zone fan system moves the air through acentral duct system and this mechanically assisted

convective loop continues to circulate stored heatat night.

Control features include a window quilt that can be lowered inside the sloping and ver-

tical glass of the greenhouses. Translucentwindow shutters fit inside all windows and can

be closed at night to prevent heat loss.

Along the south front is a trellis with re-moveable wooden slats which are taken downin winter and reinstalled in summer.

Two layers of 3/4-inch pOlystyrene perimeterinsulation wrap the entire house at the foundation

wall. All windows are double glazed and have11/2-inch thick wood-framed pOlystyreneshutters (R-6). Exterior walls have 6-inchfiberglass (R-19) insulation. Attic, roof, andexposed overhang have 9-inch fiberglass battinsulation (R-30).



Builder: Robert Brown Butler, Katonah, NY

Designer: Robert Brown Butler

Price: $60,000 (plus land)


Heat Load: 42.0 x 10· BTU /yr

Degree Days: 5732

Solar Fraction: 90%

Auxiliary Heat: 0.54 BTU / DD /ft^2

Passive Heating System(s): Direct gain Recognition

Factors: Collector(s): South-facing

glazing, clerestory windows, 368 ft^2 Absorber(s):Ceramic tile floors, masonry walls and floors Storage:Ceramic tile floors, masonry walls and floor-capacity:24,583 BTU / 0 F Distribution: Natural and forced convection Controls: Garage typethermal shutters, overhang, thermostats

Back-up: Wood burning stove, electric resistanceheaters

Domestic Hot Water: Three-panel active DHW system(84ft^2)

34

Scattered deciduous trees surround this smallrectangular ranch house on a 1-acrelot in an old orchard under development inPutnam Valley, New York. The house sitson a slight slope facing south and fits naturallyinto the protective 4-foot berming on the east,west, and north sides. Low shrubs planted on

these three sides provide additional protectionfrom the wind.

Although it is one of the few single-story housesin the neighborhood, this passive solar houseconforms to the larger, more conservative houses

by reason of its conventional cedar siding andwindow size and arrangement.

Ceiling to floor thermopane™ glass takes up theentire south wall and acts as a collector for the

passive solar heating system. Narrow panelsdivided into upper and lower casement windowsalternate with

ide panels of fixed glass giving uninterruptedsouthern exposure to the south-facing livingroom, four bedrooms, and playroom.

Heat is absorbed and stored in the masonry andceramic tile floors of all these rooms which range

in a uniform pattern with rear doors opening ontoa long, narrow hallway. This hallway separates thesouthern rooms from those on the north.

Additional solar heat is absorbed and stored in 7-foot, 4-inch high, 10-inch thick masonry walls inall rooms. Clerestory windows top these wallsand have been planned to allow natural light to

pass through to the north side of the house.

All north rooms receive heat distributed by

natural convection made possible by openingdoors from the south rooms to allow



heat to be drawn to the cooler north side. Eastand west ends of the house have as their onlyglazing two bubble windows that collect heat inthe morning and afternoon. On the building'snorth face, where dressing room, bathroomswith skylights, entrance, closets, kitchen, anddining room are located, there are few windows.

The innovative feature of this house, designedto control heat loss, is a series of overheadgarage-door-type thermal shutters. Standardcommercial garage door hardware has beenused to install these shutters inside the glass ofeach room on the south side. Each shutter hasfive 20inch panels filled with 6-inch thicktranslu-

cent insulation. Operation is by individualroom switches.

The shutters function to keep heat in on cloudywinter days and winter nights. In summer theydrop behind the glass facade to keep heat out. Atthat time the casement windows, every 10 to 12feet along the

35



south side, are opened to expel heat which mayhave accumulated between windows and shutters.An overhang along the south side partially shadesthe collector during summer and permits upperawning windows to remain open in rainy weather.

From spring to autumn, removable

screens are placed over the windows to helpreduce incident radiation. Berming around thehouse helps lower temperature extremes at the

base of the exposed sect ions. Further cooling in

summer comes from the 6-inch concrete slab on polyethylene vapor barrier base that liesunder the entire house.

The roof (R-33) and exterior walls (R-26) areheavily insulated. During extremely hot weather,

perforated ducting, with vent fans at each endunder the ridge of the roof, removes excess heat.The small north windows are caulked at theseams and fitted snugly with translucent thermalinterior shutters letting natural light in even whenclosed. Bathroom skylights are filled with 10-inch translucent insulation.

The builder expects an average of 6 inches of

snow coverage from December to March to provide extra insulation on the roof and aroundthe base of the house, with a high percentage ofthe radiation striking the snow being reflectedinto the house.

Back- p heat is supplied by a thermostaticallycontrolled, cast-iron wood burning stove set

between kitchen and playroom in a central part ofthe house fairly equidistant from all rooms.

Electric resistance heaters, controlled bythermostats, are mounted on the hall side of theinterior masonry walls. Combined with thestove these provide the back-up heating systemfor the whole house.

Domestic hot water is provided by a roof-mounted, three-panel active solar collector (84square feet).

36



The passive solar system in this house isexpected to satisfy a large part of the annualheating demands. Consequently, use ofmechanical equipment has been kept to aminimum. The designer/builder believes suchequipment not only raises initial constructioncosts and requires constant maintenance but alsodecreases the owner's appreciation of theclimate control inherent in the design.



Builder: Urban Development and InvestmentCorporation, Cambridge, MA

Designer: Brook/Elton Partnership, Cambridge,

MA

Solar Designer: Brook/Elton Partnership Price:

$65,000


Heat Load: 55.6 x 10^6 BTU/yr

Degree Days: 5634

Solar Fraction: 66%Auxiliary Heat: 2.16 BTU/DD/ft^2

Passive Heating System(s): Direct gain, indirect gain,isolated gain, sun-tempering

Recognition Factors: Collector(s): South-facing windows,greenhouse glazing, 416ft^2 Absorber(s):Concrete

block wall, concrete floor slab Storage:Concrete blockwall, concrete floor slab-capacity: 10,844 BTU/FDistribution:Radiation, natural and forced convection Controls:Vents, dampers, thermostats, jalousie

Back-up: Water-to-air heat exchanger, wood stove

30

Located near Boston, a city known for itselegant townhouses, this and other homes in i tsdevelopment take the idea of the townhouseand update it for the solar future.

Tall pine trees covered the 14 acres of land that isnow the site of the development. Except wherethey have been cleared to prevent shading ofsolar collectors or to allow the construction, thetrees were retained.

The townhouse design evolved in an era whensaving building heat was important. Homes thatshare a common wall are intrinsically energyconserving because they have less surface areaexposed to the elements. This townhouse also

benefi ts from modern insula tion technology: thenorth wall has a value of R-19 and the roof, R-35.All windows are triple- or quadruple glazed.

The large pines shield the house from cold winterwinds. Both the north and south entrances havevestibules to limit the volume of heated air lost tothe outside when a door is opened. The northwall of the home is bermed with earth to reducethe difference in the temperatures between the

two sides of the wall. Summertime cooling isachieved by cross-ventilation through the openlayout of the home and by the shade provided bythe pines.

This home uses solar heat in three ways. The firstoccurs when sunlight is admitted through thehouse's 35 square feet of south-facing windows.When the sunlight strikes the interior of the home,it turns into heat, which "tempers" the inside

temperature. This method is an incomplete solarenergy system because there is no way to



32

control the heat gain or to store it. However, by providing some daytime heating, it allows theother two systems to store a larger amount ofheat for nighttime use.

The second system collects sunlight through theglazing of the greenhouse. Some of the sunlightwhich passes through the glazing strikes a dark-colored concrete block wall where it is absorbedand turned into heat. Much of this heat passesinto the concrete block wall where it is stored. At

night, when the air temperature in the house falls below the storage wall temperature, heat isdistributed from the wall by radiation andconvection.

Not all the heat from the absorber surface of thewall is stored in the wall directly. Some of thisheat warms the air in the greenhouse. This warmair may be carried by convection through vents inthe concrete wall into the living space.

When the living space becomes hot enough, anautomatic control opens a damper to a fan-drivenduct system which pulls the greenhouse airthrough cavities in the concrete block wall intothe living room, and then through the hollowFlexicore™ concrete floor slab. There the airheats the concrete. At night, the heat isdistributed as it radiates from the wall and floorinto the living space.

The blower system is also used to even out thetemperatures in the home. It does this by drawinghot air from the ridge of the home anddistributing it throughout the living space.

This entire system is controlled by a dif-

ferential thermostat that monitors greenhousetemperatures and operates the motorizeddamper. Conventional thermostats control thefan and back-up system.

The designers chose to include little heatstorage in the greenhouse itself. Although thisdesign tradeoff allows the nighttime greenhousetemperatures to drop to near the outsidetemperature, it also allows



more of the daytime greenhouse heat to be storedfor use in the home's living space. At night, thegreenhouse functions as a buffer zone by cuttingdown convection and radiation losses from theliving space.

The home's third solar system also makes use ofthe greenhouse. Solar energy is collected throughthe roof of the greenhouse, and then through

triple-glazed windows between the greenhouseand the living space. It is absorbed by thesurface of the Flexicore™ concrete floor. Theheat is stored in the floor until the living spacecools down; the heat is distributed as it radiatesinto the room. This system is controlled by a

jalousie on the roof of the greenhouse that provides summertime shading.

In an effort to eliminate the infiltration associatedwith combustion, the designers specified anelectric back-up system. When the thermalstorage mass falls below a specified temperature,water from a standard 85-gallon electric domestichot water tank is circulated through a heatexchanger placed in front of the air circulationfan. The forced air in the duct system picks upheat from the heat exchanger and carries it to theliving space.

This townhouse is also equipped with aFranklin stove to supplement the electric

back-up system.

33



This modified 2-story gambrel Cape design specifies pre-cut post and beam construction. The site is part of a

95-acre, 20-lot development; the house is priced foryoung professionals. A 2-story greenhouse and a smallattached single-story greenhouse are prominent designfeatures. The extensive south-facing glass, however, isoriented away from the street, preserving the traditionalappearance of the house.

Three passive systems are combined with a back-upwood furnace unit to meet winter heating needs. First,in the single-story greenhouse, solar heat is collectedthrough double-glazed sliding doors and two sky-

lights. Heat is absorbed and stored in the concrete floorand in the mass wall divider between the greenhouse

and living area. During winter nights, greenhouse heatis distributed from the mass wall divider into interiorliving spaces. If additional heating of the first story isdesired during the day, French doors between thegreenhouse and living area may be opened. Operabledoors, windows, and quilted insulating shades oversouth-facing glass control heat gain.

Second, besides using heat produced by

the small greenhouse, the living area attached to itcollects direct radiation as well through the Frenchdoors.

Builder: Heritage Builders, Turner, ME Designer:

Traditional Living, Inc., Hartland, VT Solar

Designer: Traditional Living, Inc.Price: $85,000


Heat Load: 68.7 x 10' BTU Iyr

Degree Days: 7511

Solar Fraction: 45%

Auxiliary Heat: 3.77 BTU/DD/ft^2

Passive Heating System(s): Sun-tempering, direct gain,isolated gain

Recognition Factors: Collector(s): Greenhouse glazing,skylights, glass doors and windows, 279 ft^2Absorber(s): Greenhouse floor, brick pavers onconcrete slab, greenhouse mass wall Storage:Rock storage bed, mass floor and wall-capacity: 7489BTU/F Distribution: Radiation, natural and forcedconvection Controls: Moveable quilt insulatingshades, exterior bamboo roll shades, roomthermostats, and sensor in rock bed

Back-up: Central airtight wood stove, electricresistance heater

Domestic Hot Water: Flat-plate collector, doublewalled heat exchanger

44

L tl th 2 t h ll t l h t Th di t ib ti t f l h t f thi til ti Th hi h l f i id t



Lastly, the 2-story greenhouse collects solar heatthrough double-glazed fixed panels and slidingdoors. Because there is no thermal mass in thegreenhouse itself, the heat accumulates and risesthrough the floor to the peak of the upper level ofthe greenhouse.

When the air temperature at the peak reaches90°F, a fan is activated by a thermostat and pullsheated air through a duct into a rock storage binlocated beneath the smaller greenhouse. Cool air

from the rock bed is returned to this greenhousethrough ducts.

The distribution system for solar heat from thisrock bed is integrated with the back-up woodstove. The duct system is equipped with an air-handler that features a reversible fan andmotorized damper. This draws heat out of therock bed for distribution to living and sleepingspace.

Nighttime heat losses are controlled by interiorgreenhouse doors, creating a buffer zone acrossthe south glazed wall.

Because summer temperatures in NewEngland are moderate, cooling can be ac-complished easily through shading and

cross-ventilation. The high angle of incidentsummer sunlight prevents significant heatabsorption by the mass wall or interior floors, andopening the skylight, glass slidingdoors, and interior doors permits cross ventilationthrough the upper and lower levels. The largegreenhouse can also be used as a porch withshading provided by a stairway, the second-floordeck and operable exterior bamboo shades.



St. Charles is a new planned community insouthern Maryland. In order to enhancemarket acceptance of passive houses, thebuilder chose the best selling model homedesign for modification with passive solar heating and cooling features. Also includedare active solar panels to heat domesticwater. The rectangular house has beenlocated so that its long dimension runs

from east to west. Its basic wall construc-tion is 2- x 6-inch wood studs with fullfiberglass batt insulation, 1/2-inchinsulatingsheathing, and aluminum siding (R-22).Inthe roof trusses, 6-inch batts are installedwith an additional 6 inches of celluloseblown in over them (R-43).

All windows are double glazed and arecomplemented by roll-down insulating cur-tains (R-15)to further cut heat loss at night.

Few of the windows are on the east or westelevations, and the amount of south-facingglazing was increased to 260square feet.This glazing includes five sliding doors, oneeach to the kitchen and dining room andthree to the family room, and a sun gardenwindow in the kitchen. All south windowshave exterior roll-down awnings to blockthe rays of high altitude summer sun.

With all awnings and south-facing insulatingshades raised, solar energy is collected

through the south-facing windows for day-time heating on cold weather days. Some of the energy warms the rooms immediately,while the rest is absorbed by the tile floor-ing for storage in the floor slab that is 6 in-ches thick for the entire southern half of the house. A skylight of double-layer acryliclocated over the stairwell also collects solar

heat for the stairwell and the upstairs



pgallery.

Convection induced by the heated roomsdistributes warmth to spaces without directaccess to sunlight. In addition, heated air from the kitchen, dining room, and familyroom on the first floor is distributed to thebalance of the house through the ducts of the back-upheating system by a blower that pulls air in from those rooms. At night,with all shades drawn, heat radiates from

the thickened floor slab, inducing convec-tion to further heat the spaces. The insulat-ing curtains on all windows control the lossof heat at night. The skylight is equippedwith a moveable shutter (R-6)that alsohelps to control heat loss.

Awnings are extended in summer to reduceheat gain, and the skylight is opened toprovide natural exhaust for hot air. Thecooling system consists of eight 50-footsections of drainage pipe located 4 feetbelow grade with a common inlet on thesouth side of the house which receives

prevailing summer breezes. Air entering thesystem is cooled by the earth before itenters the house and, along with naturalventilation, keeps the house comfortable.

81



This compact, 2-story house combinesthree methods of solar collection for heat-ing: direct radiation, Trombe wall, glazing,and a greenhouse. At the upper level,direct solar radiation is absorbed andstored in a 12-inchdeep by 30-inch wideconcrete ledge located at windowsill heightand running the l ength of the l iving/diningroom. The block wall on the lower floor serves as the absorber and storage ele-ment for both the Trombe wall system andthe adjacent greenhouse. Heat risesthrough the floor vents from the Trombewall and greenhouse for distribution to theliving/dining area on the upper level.Cooler air flows down through floor ventsalong the north side of the house to thebasement, where it re-enters the green-house or Trombe wall through intake vents

near the floor. Through-vents are located inthe second bedroom on the house's southside to the first bedroom on the north. Atnight heat radiates from the mass slab,Trombe wall, and greenhouse wall to the in-terior spaces.

Overnight, the greenhouse is shut off, and,

to control heat loss through all windows andvents, they are closed with curtains. Sum-mer overheating is controlled by overhangsand additional fold-down panels above theTrombe wall. Both the greenhouse andTrombe wall haveseparate exterior vents for exhaust cooling in the summer.

As a conservation measure, earth isbermed to a 7-foot depth at the north sideof the house; insulation values are R-18andR-33in the walls and ceilings.



This compact 2-level house includes suchdesign features as major glass areas,diagonal wood siding, and a vaultedclerestory. The building site slopes gentlyto the south away from the street, whichruns along the high north boundary of the

lot; a recreation area guaranteeing futuresolar access is on the low south boundary.Prevailing winter winds are deflected fromthe house by evergreens on the northwestand by shrubs adjacent to the north, east,and west walls of the house. Additionally,all sides of the lower floor, except thesouth, are buried, effectively blocking mostinfiltration to this level.

The lower level includes an entrancethrough the 2-car garage, a laundry room,

and a playroom. The major living spacesare located on the upper level.

Three passive collection systems are usedin this house. The first is 150square feet of double-glazed clerestory windows. The sec-

ond is a 120square-foot double glass,direct solar heating system. The third is60square feet of double glass that heatwater-filled tubes.

Absorp tio n of heat for the direct system in-cludes the surface of the slab in the lower level and the plaster surface of the northmasonry wall of the upper level. Storage of this absorbed heat is in the mass of themasonry floor and wall. The 12-inchdiam-eter water tubes both absorb and store heat.

Distribution of heat is by radiation from the



masonry wall and concrete floor. Naturalconvection distributes heat from the water tubes. Cool air enters a vent in the bottomof the tube enclosure, contacts the warmtubes, is heated, and rises through a ventat the top of the tube enclosure into the liv-ing spaces above.

Control of the solar radiation is by fixedoverhangs and seasonal shading panelsthat eliminate unwanted heat gains. The in-

direct gain system can be controlled bymoving covers over the water tube modulesto stop transfer of heat up into the livingspaces. Throughout the summer monthssun is blocked from reaching the tubes byfixed shading louvers above them.

Additional energy-conserving features of this house include: operable windows inhigh spaces to encourage natural ventila-tion during the cooling season; good walland ceiling insulation; programmable ther-mostatic control of the back-up heatingsystem; energy-saving appliance and fix-

tures; and an outside air source convection-type fireplace with glass doors.



enclosed space in front of the utility room. Solarradiation is collected through fixed fiberglasswindows and is absorbed and stored in the waterwall. At night, the stored heat rises to the ceiling

by convection, and a vent allows hot air to be

distributed into the master bedroom above thewater wall whenever the vent is opened. Thesecond water wall is separated from anotherlower-level bedroom by folding doors. Incomingsolar radiation is absorbed and stored in thewater-filled tubes. When the folding doors areopen, the bedroom is heated by radiation fromthe tubes.

The vented 2-story thermosiphoning Trombewall collects heat through southfacing fiberglass

panels, and then absorbs and stores it in massmasonry. During the

Builder: EVOG Associates, Inc., Hebron, NH

Designer: EVOG Associates, Inc.

Solar Designer: EVOG Associates, Inc. Price:

$59,000

Net Heated Area: 1348 ft^2 Heat

Load:70.3 x 10^6 BTU/yr Degree

Days: 8177

Solar Fraction: 59%

Auxiliary Heat: 2.66 BTU /DD /ft^2

Passive Heating System(s): Direct gain, indirect gain,

isolated gain, sun-tempering

Recognition Factors: Collector(s): South-facing fiberglassglazed panels, 336 ft^2 Absorber(s):

Masonry Trombe wall, water walls, concrete mass floorsurface Storage: Masonry Trombe wall, water walls,concrete mass floor-capacity: 6493 BTU/F Distribution:Radiation, natural convection Controls: Manuallyoperable Trombe wall vents, dampers and vents, interiordoors

Back-up: Electric resistance heater (27,600 BTU /H), wood burning stove

46

day, when the door to a third bedroom is open,



y, p ,heated air is drawn through an open vent in theTrombe wall and into the upperlevel kitchen,living room, and dining room and then backthrough this third bedroom on the lower level.

The second-story rooms also receive directradiation, which is stored in concrete floors. Atnight, heat from the water walls, Trombe wall, andmass floors is distributed by being radia ted backinto living and sleeping spaces. Vents in the

Trombe wall are manually closed to preventreverse thermosiphoning.

In the summer, cross-ventilation induced byopening windows, cools the house. Overhangs on both levels provide shade and minimize heat gain.

47



This contemporary Connecticut design reflectsstyling that has had wide market acceptance inthe suburban Hartford area. The house is set intoa south-facing slope which provides earth-

erming for the lower level on the east, west, and

north; this siting enhances exposure to summerreezes while reducing exposure to winter winds.Winter heat loss is further limited by the garageon the north side and the air-lock vestibule on theeast; by fiberglass insulation with R-values of 21in the walls, and 34 in the ceiling and roof; by a

buffer zone of low-use spaces on the north; and by insulating shades or shutters on all glazing.

During winter days, solar heat is collectedthrough double-glazed east-, west-, and south-facing windows. On the lower level,

heat is absorbed and stored in the concrete walls,and in concrete and tile floors of the bedrooms.Additional storage is provided

by the masonry walls of the 3-story stairwell.Stored heat is later distributed as it radiates back

into the stairwell, living room, and sleepingspaces when interior temperatures drop. Wheninterior windows between the stairwell andupper-level bedrooms are open, solar-heated airwill be distributed to these bedrooms byconvection. Excess solar heat from the lower-level bedrooms is distributed to upper levelswhen bedroom doors are open.

Solar heat can also be distributed throughout thehouse by the air handling unit in the heat pump

back-up system. Every year in the fal l, a damperin the cetl-

Builder: Hartford-West, Inc., West Simsbury, CT

Designer: Richard Reinhart, Farmington, CT Solar

Designer: Energy Research Group, Farm-ington, CT

Price: $150,000

Net Heated Area: 2200 ff^2

Heat Load:99.9x10^6 BTU/yr

Degree Days: 6350

Solar Fraction: 35%

Auxiliary Heat: 4.69 BTU/DD/ff^2

Passive Heating System(s): Direct gain, sun-tempering

Recognition Factors: Collector(s): South-facing glass,396 ft^2 Absorber(s): Concrete wall and floor, tile floorStorage: Concrete wall and floor capacity: 17,349 BTU/ F Distribution: Radiation, natural and forcedconvection Controls: Vents, shutters, damper, operableshades, insulated panels

Back-up: Air-to-air heat pump (35,000 BTU /H), electricresistance heaters

Domestic Hot Water: Flat-plate collectors (74 ft^2),120-gallon storage

52

ing-Ievel return air vent is manually opened. The is removed from the attic vent in the stairwell



fan in the air handler pulls solar-heated air fromthe top of the stairwell through the return duct anddistributes it to living and sleeping spaces via theduct system. During winter nights, heat loss iscontrolled by manually closing exterior insulatingshades on stairwell glazing and. interior insulatingshades on all other windows.

To reduce solar heat gain during the summer, theshades can be closed during the day and then

opened at night to re-radiate house heat outside.At the beginning of the cooling season, a panel ofrigid insulation

ceiling, and the damper is opened. If the exteriorwindows in the stairwell are opened and theupper windows are closed, then cool air is pulledup through the stairwell, and hot air is exhaustedthrough continuous ridge vents in the attic.Whole house cross-ventilation is induced byopening other windows and skylights. If the floorlevel return vent in the upper hall is opened, theair handler can distribute cool air

pulled into the stairwell from outside.

A Sunworks™ active solar system heatsdomestic water with four collectorsmounted on the roof.



All of the south-facing windows on the first floorof this house and most of those on the secondfloor are part of a greenhouse that spans the lengthof the house. There is one set of sliding glassdoors between the greenhouse and the living roomas well as another set in the family room. The

balance of the wall is covered with water-fil led

55gallon drums stacked two high and lying ontheir sides perpendicular to the greenhouse. Thiswater storage system is topped by a layer of 31/2inch fiberglass batts and a plywood shelf for

plants on the greenhouse side and books on theliving room side. Above the shelf, the two roomsare separated by a conventional 2- x 4-inch wallwith 31/2-inch batts. The water wall opening intothe greenhouse is glazed while the opening on theliving room side is covered by polished aluminumVenetian blinds.

While the greenhouse is a 2-story space, thecenter portion of the upper level is occupied bythe center bedroom, which extends to the exteriorwall. The central bedroom does have an openingon each side into the greenhouse, and each bed-room to either side of the central bedroom hastwo sets of sliding windows opening into the

greenhouse space.

The system collects heat in winter through all thegreenhouse glazing, and the heat is absorbed andstored by the dark slate floor and the steel drums,whose ends are covered with a selective coatedcopper foil for improved absorption. Directsunlight is also collected in the center bedroomupstairs. When heat is needed in the house, theVenetian blinds allow heat to be distributed intothe rooms by radiation from

Builder: Suncatcher Construction, Shelton, CT Designer:

Wormser Scientific Corporation, Stam-

ford, CT

Solar Designer: Wormser Scientific Corporation Price:

$115,000

Heated Area: 2178ft^2 Heat

Load: 64.7BTU/yr Degree

Days: 5897

Solar Fraction: 58%

Auxiliary Heat: 2.05 BTU / DD / ft^2

Passive Heating System(s): Isolated gain, sun-

tempering

Recognition Factors: Collector(s): Greenhouse glazing,second-floor glazing, 349ft^2 Absorber(s):Slate floor in greenhouse, black chrome coating onends of 55-gallon steel drums Storage: 110 gallons ofwater by wood stove, 1540 gallons of water inwaterwall-capaclty:38,200 BTU/F Distribution:Radiation Controls: Sliding glass doors, Venetian

blinds, insulating shades, fan, overhang

Back-up: Electric air-to-air heat pump (19,500BTU/H)

40

these drums, allowing stored heat from the woodstove to heat the room after the fire has burned

the water wall storage. When the sliding glassdoors are opened heat is distributed by



stove to heat the room after the fire has burnedout.

These passive features are augmented by goodconservation measures. The garage is located tothe north and west of the house to block winterwinds. There is a double airlock entry between thegarage, the rear entry, and the house, while thefront entrance to the house is through thegreenhouse. All walls are insulated with 31/2-inchfiberglass batts and 2-inch polystyrene sheathing

(R24), and 12-inch batts (R-40) are installed inthe ceiling joists.

doors are opened, heat is distributed byconvection from the warmer greenhouse into thehouse. Similarly, windows in the side and center

bedrooms open into the upper greenhouse space toreceive the warm air flow.

To control heat loss at night, insulating shades are pulled down over the windows and glass doors(combined value R-15). If necessary, the woodstove in the family room is used. Two 55-gallonwater-filled drums are located next to the stove to

absorb and store heat. A door in the family roomopens to expose more surface area of

41



This traditional ranch-style home has itsnorth side facing the street, which makesits appearance similar to other homes inthe subdivision. The site slopes gently tothe south and has no significant obstructionof its solar access.

Solar collection occurs on the south side of the building through two pairs of slidingglass doors and the clerestory windows of an atrium, and at eleven glass and plasticglazed panels divided (six and five) be-tween two collection walls in the master

bedroom and great room.

Heat is absorbed in the atrium and thehallway behind it by 1/2-inchquarry tilepavers, and stored by the 4-inch concreteslab beneath. In the collection wallabsorption occurs in the black-enameledcorrugated aluminum set within the spacebetween the glazing and the interior wall.Heated air from this space is distributed inthe following manner: as it rises to the top

of the wall, it is pulled through a duct by afan to the bottom portion of a doubleplenum. This plenum runs along the bottomof the wall; from here the heated air is fedinto every other core of double-core blockpositioned to form a concrete duct all theway back to the north wall. The hot air travels down one core of the block to thenorth wall, where a distribution duct directsits flow back down the other core, where itflows back into the collection space of thewall to be reheated and redistributed in the

same manner. The fan is thermostaticallyset to cut out if the temperature of the ab-sorber wall drops below a set point.

Meanwhile, the solar air that has passedthrough the floor has had its heat absorbedby the block and the 4-inch concrete slablaid over the block, causing it to radiate in acontrolled manner up into the living areas. Additional heat is available from the atriumif all interior doors to that area are left open

and the ceiling fan is turned on; this ar-rangement will cause hot atrium air to be



gdistributed to the inner living areas. Heatloss is controlled with manually operatedroll-down window quilts on all windows.

Back-up heat is available from a heatilator fireplace in the great room-drawing itscombustion air from the outside-and elec-tric resistance strips in the air condition-ing/heating unit. This unit's duct systemruns through the attic and reaches allrooms including the atrium.

In the summer mode, manually operateddampers in the collection wall/duct systemare switched so that hot air at the top of thewall is exhausted outside by a separateduct fan. But the heating duct fan is alsoused on summer nights to draw cool air inand circulate it through the block and con-crete slab floor. This will help keep thehouse cool during the next day. Heat gainis controlled in summer by fixed overhangson all south-facing glass, and by an exhaustfan in the atrium. If windows in all rooms

are left open, as well as interior atriumglass doors, this fan can change air in thehouse at the rate of once every sixminutes. For peak cooling needs there iscentral air conditioning.

The insulation values for the house are R-30for the roof and R-23in the walls. All win-dows and glass doors are double glazed,and all entries are through air-lockvestibules.



The east, north, and west sides of thissmall rectangular house are three solidconcrete block walls that are backed intothe south-sloping side of a hill. The south-facing side of the house features two levelsof glass. The site is on five acres of rela-tively uncleared land in a rural subdivisionon a ridge of the Shenandoah Valley inWarren County, Virginia.

Collectors for the passive solar system arepanels of double glass in the ground floor where the living room, flanked on each sideby a bedroom, is located. On the upper floor, where a central family room looks

down into the living room, a den to the west,andthe kitchen/dining area to the east, a rowof clerestory windows collects sunlight.

Concrete slab floors and the 12-inch solidwalls absorb and store the direct solar heat. In addition, a specially insulatedstorage room, virtually underground at thecenter rear of the house, holds 1,1521-gallon plastic containers for supplementalstorage.

Heat is radiantly distributed from thestorage walls and floor, and to avoid waste,a damper and fan system draw stratified

air from the top of the clerestory area intothe remote ater storage closet D ring



the remote water storage closet. Duringperiods of overheating, air can also bedrawn through floor ducts beneath the con-crete slab and discharged into the storageroom. The storage closet can dischargethrough a series of distribution ducts toprovide nighttime heating through the base-board upstairs and from the ceiling. of theground floor.

All windows are fitted with hand-operated

window quilts to control nighttime heatloss. A wood stove and a heat pump withan electric resistance coil provide back-upheat. When temperature in the storage areaand the rest of the house is below the re-quired level, auxiliary heat comes on and isdistributed through slab vents and ducts.

In the summer, excess heat is releasedfrom the house through a vent stack whosefan pulls air through the hollow floor slaband exhausts it via a roof ventilator. Lower sections of the upstairs glass open for sum-mer ventilatio'n.



This Cape Cod style, single-story, 3 edroomhome is located on a level, treeless lot in a 13-unit subdivision. Its energy-conserving featuresinclude: automatically operated insulatingshades for the double-glazed, south-facing win-

dows; the separation of living spaces from thenorth wall by a continuous hallway; the locationof a buffer zone along the north wall; and wind

protec tion provided by the garage.

The entire south wall of the house is in effect adouble-glazed collector that includes a slidingdoor that opens into the living room. Livingspaces are arranged along the east- est axis of thehouse, and, except for the living room, areseparated from south facing fixed windows bymass storage

alls. A narrow greenhouse occupies the space between the mass wall and glaz ing in f ront of thekitchen and dining room. The Trombe wall infront of the bedroom is separated from the glazing

by a narrow maintenance space.

During winter days, solar radiation is absorbedand stored by the Trombe and mass storage wallsand concrete floors; when bedroom doors andmanually operated upper Trombe wall vents areopened, convective circulation distributes heat tothe living spaces. At night, the mass walls andfloors radiate stored heat into the interior.Closing shades, hall doors, and wall ventscontrols both radiant and convective heat losses.

Builder: Pierre Realty, Charlotte, VT

Designer: Aukerman Associates, Burlington, VT Solar

Designer: Harris Hyman and Aukerman

Associates, Lamoine, ME

Price: $67,500


Heat Load: 97.3 x 10^6 BTU /yr

Degree Days: 7876

Solar Fraction: 54%

Auxiliary Heat: 3.07 BTU / DD/ft^2

Passive Heating System(s): Direct gain, indirect gain,sun-tempering

Recognition Factors: Collector(s): Double-glazed southwall, 443 ft^2 Absorber(s):Concrete mass and Trombe

walls, greenhouse mass floor, living area mass floorStorage: Concrete mass and Trombe walls, greenhousemass floor, living area mass floor-capacity: 35,711 BTU/ 0 F Distribution: Radiation, natural convectionControls: Manually operable doors, windows, Trombeand mass wall vents, insulating shades, ceiling vents

Back-up: Two wood burning stoves, electric resistanceheaters

Domestic Hot Water: Passive preheat piping set into floorslab

50

Summer convective cooling is maximized byopening north windows hall doors ceiling vents



opening north windows, hall doors, ceiling ventsabove the Trombe and mass walls, and the floor-level return register at the base of the walls. Theinduced cross ventilation pulls cool air in throughnorth windows and vents hot air out through thecontinuous ridge vent.

A passive domestic water preheat system is setinto the concrete floor in the living room. The

pipes rest in a bed of very fine granite chips between bricks just below the surface of the s lab.The pipe system is covered with slate, and isexpected to provide about 50 percent of theannual domestic hot water load.

Build Solar

Documents

Transcript of Build Solar