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 Mobile ViewAIR CONDITIONING & HEAT PUMP SYSTEMS ENERGY SAVINGS in buildings ICE DAM PREVENTION INSULATION IDENTIFICATION GUIDE INSULATION INSPECTION & IMPROVEMENT AIR BYPASS LEAKS AIR CHANGE RATE ACH HEAT SAVINGS AIR FILTERS for HVAC SYSTEMS AIR LEAK DETECTION TOOLS AIR LEAK MINIMIZATION AIR LEAK SEALING PROCEDURE AIR SEALING STRATEGIES ANIMAL ALLERGENS APPLIANCE EFFICIENCY RATINGS ASBESTOS FLOORING HAZARD REDUCTION ASBESTOS-FREE INSULATION MATERIALS ASBESTOS IDENTIFICATION IN buildings ATTIC LEAKS, CONDENSATION & MOLD ATTIC VENTILATION BACKDRAFTING HEATING EQUIPMENT BASEMENT CEILING VAPOR BARRIER BASEMENT HEAT LOSS BASEMENT LEAKS, INSPECT FOR BASEMENT WATERPROOFING BATH & KITCHEN DESIGN GUIDE BATHROOM VENTILATION BIOGAS PRODUCTION & USE BLOWER DOORS & AIR INFILTRATION BLOWER FAN CONTINUOUS OPERATION BLOWER FAN OPERATION & TESTING BLOWN-IN INSULATION BRICK LINED WALLS BRICK VENEER WALL INSULATION BRICK VENEER WALL Loose, Bulged BRICK WALL DRAINAGE WEEP HOLES BUCKLED FOUNDATIONS due to INSULATION? BUILDING NOISE DIAGNOSIS & CURE CATHEDRAL CEILING INSULATION CATHEDRAL CEILING VENTILATION CEILING FINISHES INTERIOR CEILINGS, DROP or SUSPENDED PANEL CEILINGS, PLASTER TYPES CHIMNEY INSPECTION DIAGNOSIS & REPAIR COOLING LOAD REDUCTION by ROOF VENTS COMBUSTION AIR for TIGHT BUILDINGS CONDENSING BOILERS/FURNACES DAMAGE CONDENSATION or SWEATING PIPES, TANKS COOLING LOAD REDUCTION by ROOF VENTS CRAWL SPACES DEFINITION of Heating & Cooling Terms DEHUMIDIFICATION PROBLEMS DEW POINT CALCULATION for WALLS DEW POINT TABLE - CONDENSATION POINT GUIDE DUCT SYSTEM & DUCT DEFECTS REMOTE ELECTRIC POWER, PHOTOVOLTAIC ELECTRIC HEAT ELECTRIC POWER, PHOTOVOLTAIC, REMOTE SITE ENERGY SAVINGS in buildings ENERGY STAR PROGRAM EVAPORATIVE COOLING SYSTEMS FIBERGLASS INSULATION FIBERGLASS HAZARDS FIBERGLASS INSULATION MOLD FLASHING MEMBRANES PEEL & STICK FLAT ROOF MOISTURE & CONDENSATION FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP FLOODS IN buildings-mold FLOOR COVERING for OVER THERMAL MASS SLABS FLOOR TYPES & DEFECTS FLOOR TILE HISTORY & INGREDIENTS FOUNDATION WATERPROOFING FRENCH DRAINS FRAMING DETAILS for BETTER INSULATION FRAMING DETAILS for DOUBLE WALL HOUSES FRAMING METAL STUD PERFORMANCE FREEZE-PROOF A BUILDING FROST HEAVES, FOUNDATION, SLAB GREEN BUILDING CONSTRUCTION CODES GUIDES GREENHOUSE DESIGN for SOLAR HEATING HEAT LOSS in buildings HEAT LOSS DETECTION TOOLS HEAT LOSS INDICATORS HEAT LOSS PREVENTION PRIORITIES HEAT LOSS R U & K VALUE CALCULATION HEAT LOSS RATE CALCULATIONS HEAT TAPES & CABLES on Roofs for Ice Dams HEATING COST SAVINGS METHODS HOT ROOF DESIGNS: Un-Vented Roof Solutions HOUSEWRAP AIR & VAPOR BARRIERS HOUSE DOCTOR, how-to be HUMIDITY LEVEL TARGET ICE DAM PREVENTION INDOOR AIR QUALITY & HOUSE TIGHTNESS INDOOR AIR QUALITY IMPROVEMENT GUIDE INSULATION CHOICES Insulation Air & Heat Leaks INSULATION FACT SHEET- DOE INSULATION for GREENHOUSE or SOLARIUM INSULATION IDENTIFICATION GUIDE INSULATION INSPECTION & IMPROVEMENT INSULATION LOCATION - WHERE TO PUT IT INSULATION MOLD INSULATION R-Values & Properties INSULATION IDENTIFICATION GUIDE INSULATION INSPECTION & IMPROVEMENT INSULATION LOCATION - WHERE TO PUT IT INSULATION MOLD INSULATION R-Values & Properties LEED GREEN BUILDING CERTIFICATION LEED Building Designation & IAQ LIGHTING, EXTERIOR GUIDE LIGHTING, INTERIOR GUIDE LOG HOME ENERGY EFFICIENCY LOG HOME GUIDE LOG HOME WALL INSULATION VALUES METHANE GAS SOURCES MOBILE HOME INSPECTIONS MOISTURE CONTROL in BUILDINGS MOLD in FOAM INSULATION, RESISTANCE MOLD INFORMATION CENTER Nanomaterials Hazards NOISE / SOUND DIAGNOSIS & CURE NOISE CONTROL for HEATING SYSTEMS NOISE CONTROL for FLOORS NOISE CONTROL for PLUMBING NOISE CONTROL for ROOFS ODORS & SMELLS DIAGNOSIS & CURE PAINT FALURE, DIAGNOSIS, CURE, PREVENTION PASSIVE SOLAR DESIGN METHOD PASSIVE SOLAR HEAT PERFORMANCE PASSIVE SOLAR HOME, LOW COST PHOTOVOLTAIC POWER SYSTEMS PLASTER & BEAVERBOARD & DRYWALL PASCAL CALCULATIONS RADIANT BARRIERS RADIANT HEAT RADIANT HEAT Floor Mistakes to Avoid RADIANT HEAT TEMPERATURES RADIANT SLAB FLOORING CHOICES RADIANT SLAB TUBING & FLUID CHOICES ROOFING INSPECTION & REPAIR ROOF VENTILATION SPECIFICATIONS ROT, FUNGUS, TERMITES ROT, TIMBER FRAME SEARS KIT HOUSES SHEATHING, FOIL FACED - VENTS SOLAR ENERGY SYSTEMS BLOCKBED RADIANT FLOORS - SOLAR DESIGN FLOOR, CONCRETE SLAB CHOICES FLOOR, CONCRETE SLAB POURED FINISH GLASS vs HEAT MIRROR SOLAR GAIN/Loss GREENHOUSE DESIGN for SOLAR HEATING GREENHOUSE / SUNSPACE GLARE PASSIVE SOLAR DESIGN KEY ELEMENTS PASSIVE SOLAR DESIGN METHOD PASSIVE SOLAR ENERGY MONITORING PASSIVE SOLAR FLOOR TILES, PHASE CHANGE PASSIVE SOLAR HEAT PERFORMANCE PASSIVE SOLAR HOME, LOW COST PASSIVE SOLAR PERFORMANCE PROBE PASSIVE SOLAR Roof & Window Overhangs PHOTOVOLTAIC POWER SYSTEMS POLYCARBONATE GLAZING REMOTE ELECTRIC POWER, PHOTOVOLTAIC ROCK-BED SOLAR HEAT STORAGE DESIGN SLAB INSULATION, PASSIVE SOLAR SLATE THERMAL MASS for SOLAR HEAT STORAGE SOLAR COLLECTOR AIR or GAS COLLECTION SOLAR COLLECTOR EFFICIENCY COMPARISONS SOLAR COLLECTOR FILMS SOLAR COLLECTOR OUTGASSING SOLAR COLLECTOR WOOD HOUSINGS SOLAR GAIN CALCULATION SOLAR HEATING SYSTEM DESIGNS SOLAR HOT WATER HEATERS SOLAR HOUSE EVALUATION SOLAR MODULE MANUFACTURERS SOLAR SHADES & SUNSCREENS SOLAR SHADES, LOW-E EFFECTIVENESS SOLAR WATER DISINFECTION SOLAR HOT WATER HEATERS SUNSPACE DESIGN for SOLAR HEATING SUNSPACE GLAZING for SUNTANNING STORM WINDOW INTERIOR STORM WINDOW PLASTIC CHOICES STORM WINDOW WEEP HOLES SUNGAIN, FILMS, LOW-E GLASS SUNSPACE GLAZING for SUNTANNING SWIMMING POOL SOLAR HEAT, INDOOR SWIMMING POOL SOLAR HEAT, OUTDOOR DIAGNOSIS THERMAL MASS in buildings SOUND CONTROL in buildings STAIN & BIODETERIORATION AGENT CATALOG STAINS on buildings - QUICK GUIDE STAIN DIAGNOSIS on BUILDING EXTERIORS STAIN DIAGNOSIS on BUILDING INTERIORS STAINS on INDOOR SURFACES: PHOTO GUIDE STRESS SKIN INSULATED PANELS STUCCO OVER FOAM INSULATION SWEATING (CONDENSATION) on PIPES, TANKS THERMAL EXPANSION of MATERIALS THERMAL MASS in buildings THERMAL MASS FLOOR SLABS THERMAL MASS in UPSTAIRS THERMAL MASS WALL DESIGN THERMAL MASS in HOMES - STUDY THERMAL MASS TRADEOFFS, HEATING vs COOLING THERMAL TRACKING & HEAT LOSS VAPOR BARRIERS & AIR SEALING at BAND JOISTS VAPOR BARRIERS & CONDENSATION in buildings VAPOR BARRIERS & HOUSEWRAP VAPOR CONDENSATION & BUILDING SHEATHING VENTILATION in buildings WATER ENTRY in buildings WIND ENERGY SYSTEMS WIND TURBINES & LIGHTNING WIND WASHING INSULATION At EAVES WINDOWS & DOORS WINTERIZE A BUILDING WOOD, COAL STOVES & FIREPLACES WOOD STOVE SAFETY ZONE VALVES More Information |
This article discusses the actual vs claimed performance of passive solar designs and an explanation of why those figures differed in a 1980's passive solar home design are detailed. Illustration at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Readers should also see PASSIVE SOLAR HEAT PERFORMANCE. Also see ROCK-BED SOLAR HEAT STORAGE DESIGN and see SOLAR ENERGY SYSTEMS our solar energy home page, PASSIVE SOLAR DESIGN METHOD, and SOLAR HOUSE EVALUATION. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website. A Probe of Passive Solar System PerformanceSteve Bliss, associate editor, Solar Age Magazine This article appears in original form (the PDF links just below) and an updated/expanded web article below.
The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. Passive Solar Performance: Actual, Claimed, & EvaluatedMany passive solar homes surpass the thermal performance goals set by their designers. This success is often the result of careful management and low indoor temperatures, or conservative calculations to begin with. IN too many homes, though, great performance comes only at the expense of good design, or worse - the homes demand a heavy sacrifice of comfort from the occupants.
In addition to the usual siting and layout requirements of passive solar design, views to all directions were to be preserved, the solar collection space was also to serve as living space, and the heating program was to be flexible - providing heat only when and where it was needed. Glass and lightly stained cedar interplay in the handsome geometry of the southern facade of the Langley house designed and built by the Bourgeois-Moran team. The brick mass wall in the sunspace provides a decorative boundary for the kitche workspace (see sketch below). Warmed air collected from the greenhouse in the upper plenum is ducted to the remote rockbed, which boosts the forced-hot-air auxiliary furnace. IN summer, clerestory glazing is opened for whole-house venting. Architecturally, this house in western Massachusetts was and remains an unqualified success; the owners treasure their home. Yet thermal performance of this passive solar implementation at the time of this investigation was not encouraging. A close examination of the project suggested why passive solar performance goals had not been met and what steps might be taken to correct the problems. As is the case with good custom homes - solar and non-solar alike - the initial design grew out of hours of conversation between the owners and the architect, probing their "philosophy of living" and feelings about the particular setting. Ken and Joan Langley and their teenage children were swept up in the design process. In their words, "we really got hooked on the idea of building when (we) suddenly realized how much the house would really be ours." The plan provided for primary living spaces cantilevered over the south-sloping landscape toward mountain views and summer-shading deciduous trees. As cooking was a central activity of the Langley family, a large sunspace/kitchen area was designed as the spatial and thermal focus of the home. With a hot-air above and rockbed below [for heat storage], the kitchen area would be the most consistently heated space. The adjoining two-story sunspace would function as both eating nook and circulation zone, therefore requiring few furnishings that might shade the direct-gain thermal mass. At the cost of losing a measure of thermal efficiency, the solar collection area was included as primary living space. R-9 night insulation was planned to minimize heat losses. The Langleys were also a musical family. For occasional performances with family and friends, the expansive living room, opened up with west-facing windows, adjoins a raised music area. The platform serves nicely as an informal stage. Two teenage daughters [in the 1980's] needed smaller private spaces. The young women ended up with compact but exciting two-story bedrooms with large sleeping lofts. All the rooms that face south can be opened to the sunny core of the home. Operable doors and windows are opened or closed as passive heating or cooling is required. For primary space heating, the Langleys, who each worked but anticipated soon being empty-nesters, wanted a flexible program that would deliver high-grade heat to peripheral rooms quickly, and only as needed. A passive-hybrid, forced hot air furnace system was chosen for its simplicity and economy. The environmentally attuned design team placed the garage to the northwest as a wind buffer with the driveway to the south for solar-assisted snow removal. Similarly, a woodbin to the east of the entry is exposed to the south to help keep the wood dry. Judiciously placed plantings and a sparing use of glass kept the northern facade relatively enclosed for minimal heat loss. Design for Hybrid Heating in This Passive Solar Home
Sketch at left (Barbara Putnam). The conditioned air is then ducted in-line through a Thermopride multi-fuel furnace and is passed by an auxiliary electric resistance element before being fed to the lower rooms and children's bedrooms through operable floor registers. The master bedroom is open to convective heating from the living room below, which has a backup wood stove. [Wood Burning Heaters Fireplaces Stoves]. The design/builders could not find a multi-fuel unit with built-in electric backup that met local code requirements, so they were forced to improvise with less-than-compatible components and controls. In an effort to achieve the higher efficiencies sought in active system rock storage, the consulting engineer designed a reversing system (two-way flow) with separate collection and delivery modes for heating and cooling, and an additional mode for electrically-boosted auxiliary heating. In summer, the owners open vent windows in the upper air plenum to convert it to a thermosiphoning tower, which both vents the sunspace and draws cooling air through the house. Assessing Thermal Performance of This Passive Solar DesignAccording to performance criteria supplied by the design team, the Langley home was designed to attain a Solar Savings Fraction of .37, an ambitious goal for New England, in this case requiring 460 square feet of south-facing glass. This figure indicates that 37 percent of the heat required to maintain design temperature would be supplied by solar energy. At this level of performance, 5 1/2 cords of hardwood, supplying 55 million BTUs of auxiliary heat, would be required to maintain the indoor temperature at an average of 65 degF. [Also see PASSIVE SOLAR HEAT PERFORMANCE].
The kitchen/greenhouse area rarely exceeded the high 50's. After a sunny day with no auxiliary heat, the house averaged 60-62 degF. before sunset. On these days the upper plenum reached the mid-70's, the rockbed the mid 60's, and warm air to the room approximately 60 degF. The owners reported that air from the supply registers, even when warmer than room temperature, felt cold to the skin. It's not like the 110-120 degF. air that they expected from a forced hot-air heating system. [Also see PASSIVE SOLAR ENERGY MONITORING]. While the owners were very pleased with their home, with the thoughtful and imaginative use of space, the grand views, and fine detailing throughout, they expressed disappointment in the solar performance of the building. They reported that the rockbed did not work as expected, and, in fact, was not needed since overheating was not a problem. On winter mornings, the Langleys tolerated a chilly kitchen, feeling it was the price they paid for the glass and the views. They also wished they had more control over temperatures in the master bedroom, which is always open to the living room below. When they warmed the living room by lighting the wood stove, they automatically warmed the bedroom above to a few degrees higher. The Langleys, however, liked to sleep in a cold room. The design/build team felt that the owners did not fully understand the function of the rock storage -that it was a thermal flywheel meant to stabilize temperature swings rather than to supply high-temperature air to the registers on its own. The consulting engineer, after being alerted to the problems, carefully rechecked his calculations and later visited the completed site. His measur4ements indicated a 35 percent reduction in insulation at the greenhouse due to shading (on a specific day of observation in early October, at 2:00 PM). He also noted the lack of nighttime insulation and, as water leaks had plagued the greenhouse glazing, he suspected high infiltration losses as well. The consultant who performed the calculations assumed an unobstructed southern exposure, while the owners and designer had planned to leave trees for summer shading and landscaping. After some trimming of these trees, the owners estimated a 20-percent shading loss may still have remained. As for the R-9 night insulation in the calculations, the owners planned to install some night insulation as soon as they had tackled the greenhouse leakage problems. The lack of nighttime insulation alone dramatically lowered the SSF from 0.37 to just above 0.10, raising the auxiliary heating requirements by 23 million BTUs or almost 2 1/2 cords of wood more than the original 5 1/2 estimated. The estimated shading coefficient of 20 percent at the sunspace would account for an additional loss of 6.6 million BTUS annually. If glazing repairs reduced air infiltration in the sunspace, greater savings would accrue as well. The house as a whole had a relatively high heat loss compared with passive solar homes of similar size. This was partly due to the liberal use of non-south-facing windows and the inclusion of the greenhouse as primary living space. The amenities that resulted from these design decisions must certainly be weighed in the economic equation. Assessing the Rock Bed Storage System for this Passive Solar HomeA reversing rockbed, when operated effectively, will perform at a higher efficiency than a simpler one-way-flow rockbed storage system. But the additional cost and complexity may not be justified in a passive-collection system such as the one designed for this home. Temperature gradients across the rockbed were too small to make much of a difference. [See ROCK-BED SOLAR HEAT STORAGE DESIGN.] The designers, in retrospect, tend to agree. If the whole house were brought up to design temperatures by correcting the heat loss and shading problems, then the owners would probably be more satisfied with the rockbed as "flywheel". Fine-tuning the passive solar system so that control settings, air temperatures, and blower speeds are balanced for owner comfort could help further. Despite the shortcomings in the home's thermal performance, the Langleys reported that "the home offers so much flexibility that we have found ways to make it do what we want." And as corrective measures helped bring the house in conformity with its original design criteria, it was likely to fulfill its promise as an exciting and working passive solar home. Passive Solar Home Design & Build Participants & Specifications
Building Data
Conservation Package
This article is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Questions & Answers regarding this article. Ask a Question or Search InspectAPediaHTML Comment Box is loading comments...
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