Passive Solar Passive Solar systemsystem

BY:MD.RUMAN

11131AA010

Passive Solar systemPassive Solar system Passive solar heating is defined as using solar Passive solar heating is defined as using solar energy striking windows, skylights, greenhouses, energy striking windows, skylights, greenhouses, clerestories, and mass walls in order to provide clerestories, and mass walls in order to provide heating for a house.heating for a house.

Generally, such solar collection occurs Generally, such solar collection occurs passively, without the extensive use of pumps or passively, without the extensive use of pumps or fans typically used in active solar collector fans typically used in active solar collector systems.systems.

Because heating is needed only over the colder Because heating is needed only over the colder part of the year (Sept. to May), passive solar part of the year (Sept. to May), passive solar design must also eliminate unwanted solar heat design must also eliminate unwanted solar heat gains during the summer.gains during the summer.

The use of techniques to eliminate solar gains The use of techniques to eliminate solar gains and to cool a house with the use of active and to cool a house with the use of active systems is often referred to as passive coolingsystems is often referred to as passive cooling

1. Conservation Levels: Higher than normal levels of insulation and airtightness2. Distribution of Solar Glazing: distributed throughout the building proportional to the heat loss of each zone3. Orientation: Optimum within 5 degrees of true south4. Glazing Tilt: Looking for perpendicular to sun angle in winter, although vertical efficient where lots of reflective snow cover5. Number of glazing layers: 3 to 4 for severe climates, less otherwise6. Night insulation and Low-E glazing: Greatly improves reduction of night heat losses7. Mixing passive systems can increase comfort levels.

Types of Passive SystemsTypes of Passive Systems

Direct GainDirect Gain Trombe Wall or Mass WallTrombe Wall or Mass Wall Sunspace or GreenhouseSunspace or Greenhouse Roof SystemsRoof Systems

Direct Gain SystemsDirect Gain Systems Sunlight incident on transparent Sunlight incident on transparent surfaces allows the energy to enter surfaces allows the energy to enter the living space directly and is the living space directly and is called Direct Gain.called Direct Gain.

South facing windows thus form the South facing windows thus form the basis for the simplest type of basis for the simplest type of solar heating system.solar heating system.

With some simple guidelines, this With some simple guidelines, this design is the cheapest and best way design is the cheapest and best way to incorporate solar into a house.to incorporate solar into a house.

Direct Gain Passive Solar DesignDirect Gain Passive Solar Design Surfaces should be generally Surfaces should be generally facing south (to within 20 facing south (to within 20 degrees)degrees)

Overhangs should prevent unwanted Overhangs should prevent unwanted summer gains (2 ft typical at 40 summer gains (2 ft typical at 40 degrees latitude)degrees latitude)

Window area should be 8-12% of Window area should be 8-12% of the house floor area if no extra the house floor area if no extra thermal mass is addedthermal mass is added

This amount of passive solar gain This amount of passive solar gain should provide no more than 40-should provide no more than 40-50% of the yearly heating load50% of the yearly heating load

More area may be possible if More area may be possible if additional thermal mass is added.additional thermal mass is added.

PRECAUTIONSPRECAUTIONS Excess window Excess window area can result area can result in a loss of in a loss of privacy, too privacy, too much glare, much glare, underheating and underheating and overheatingoverheating

Movable Movable insulation insulation should be should be designed to be designed to be easy to install easy to install and useand use

A Simple Direct Gain A Simple Direct Gain SystemSystem

1. Mass Distribution: spread it around evenly; 6 times glazing area (3X minimum)

2. Mass Thickness: thin and spread out better than thick. More than 4” for masonry or concrete not useful

3. Colour: Floors dark to absorb more heat, walls and ceilings lighter to reflect light.

4. Surface Covering: insulative coverings (ie. Rugs) greatly decrease performance of thermal mass

5. Concrete Block Masonry: If used, a high density with cores filled with grout

6. Floor Materials: Concrete or brick preferred. If insulating under, at least 4” thick (100mm). More than 6” (150mm) not useful.

7. Limits on Direct Gain Glazing Area: South facing glazing limited to prevent large temperature swings. 7% of floor area for low mass buildings, 13% of floor area for high mass buildings.

8. Glazing orientation: Vertical facing due south preferred. Vertical easiest to build, and easiest to shade in summer. Performance penalty for 15degrees off due south is 10% and for 30 degrees is 20% loss; so within 15 degrees recommended.

9. Night insulation: Really helpful but can be very costly.

10.Thermal Insulation: Insulation located OUTSIDE the thermal mass.

Good design is based on combining Good design is based on combining several elements and ideasseveral elements and ideas

Knowledge of seasonal changes Knowledge of seasonal changes in sun pathin sun path

Landscaping in the site planLandscaping in the site plan OverhangsOverhangs Appropriate use of thermal massAppropriate use of thermal mass Energy efficient design for the Energy efficient design for the thermal envelopethermal envelope

The Sun’s Seasonal PathThe Sun’s Seasonal PathThis path is hemisphere and latitude This path is hemisphere and latitude dependentdependent

40 Degree Latitude Sun Chart40 Degree Latitude Sun Chartshowing altitude and azimuth angles for showing altitude and azimuth angles for different months of the year and times of different months of the year and times of the daythe day

Overhangs on the South Overhangs on the South SideSide

Clerestory is also direct Clerestory is also direct gaingain

Excellent for Excellent for bringing bringing daylighting daylighting to northern to northern spaces (deep spaces (deep houses)houses)

Can use north Can use north wall masonry wall masonry heat storageheat storage

Overhang over Overhang over clerestory clerestory window shades window shades in summerin summer

Example of Clerestory Example of Clerestory HouseHouse

Thermal Storage Walls or Thermal Storage Walls or Trombe WallsTrombe Walls

Advantages:Advantages: Eliminates glareEliminates glare Lowers temperature Lowers temperature swings in roomswings in room

Vents allow Vents allow partition of energy partition of energy into daytime and into daytime and nighttime heatingnighttime heating

Sun hits entire Sun hits entire massmass

Precautions:Precautions: More expensive and More expensive and less efficient than less efficient than direct gaindirect gain

More difficult to More difficult to reduce nighttime reduce nighttime losseslosses

Best for sunnier Best for sunnier climatesclimates

Occupies valuable Occupies valuable spacespace in buildingin building

Trombe Wall with VentsTrombe Wall with Vents

Operation of Trombe WallOperation of Trombe Wall Sunlight hits the darkened mass wall and Sunlight hits the darkened mass wall and absorbed heat moves slowly across the wallabsorbed heat moves slowly across the wall

The inside surface temperature peaks 6-8 hours The inside surface temperature peaks 6-8 hours after the midday outside surface peakafter the midday outside surface peak

Operational vents allow optional controlled air Operational vents allow optional controlled air circulation into the space during the daycirculation into the space during the day

Overhang reduces wall sun exposure during the Overhang reduces wall sun exposure during the warmer monthswarmer months

Vent added to outside at the top can drive warm Vent added to outside at the top can drive warm air out in the summer and bring cooler air from air out in the summer and bring cooler air from a north venta north vent

can be used as part of a south-facing greenhousecan be used as part of a south-facing greenhouse may be retrofitted to existing houses with brick may be retrofitted to existing houses with brick or stone constructionor stone construction

SUNSPACE CONCEPTSUNSPACE CONCEPTwith mass wall addedwith mass wall added

Sunspace -- a passive solar heating system type consisting of a glassed-in room like a greenhouse, atrium or conservatory, located on the south side of a building and separated from other building spaces by a common wall.Common Wall -- a wall separating a sunspace from other living spaces.Greenhouse -- a sunspace used primarily for growing plantsProjected Glazing Area -- net glazing projected onto a single vertical wall.

Attached Greenhouses or Attached Greenhouses or SunspacesSunspaces

Advantages:Advantages: Lower temperature Lower temperature swings in adjacent swings in adjacent living spaceliving space

Flexible – can be Flexible – can be operated in many modesoperated in many modes

Provides additional Provides additional living or growing spaceliving or growing space

Works well in late Works well in late winter and spring when winter and spring when standard overhangs standard overhangs block direct gain block direct gain through windowsthrough windows

Precautions:Precautions: Price moderate to highPrice moderate to high Thermal performance Thermal performance depends greatly on how depends greatly on how it is operatedit is operated

1. Effect of orientation: optimum due south. Penalties about 5% for 30degrees off due south. More summer overheating for off south directions.

2. Use of Mass: increases space’s livability. Reduces overheating. Optimum thickness for masonry walls between 8 and 12”.

3. Area of Mass: direct gain rules apply: 3mass to 1glazing.

4. Do not glaze end walls: for both summer and winter performance.

5. Summer Venting: needs to be vented during summer especially if not well shaded.

6. Wall Colour: Direct gain rules apply, except:a. use darker colours in general as light colours tend to reflect light and heat out of the spaceb. if used as a green house, surfaces in corners need to be light to improve plant performance/life.

7. Sunspace width: 15 to 20 feet works well.8. Colour: dark colours work better to absorb

heat.9. Plants and other lightweight objects: Limit.10.Roof: Need to be able to shade it in the

summer to avoid overheating. Curtain, awnings or internal shades, OK.

11.Common Wall: Needs to be able to be closed off from main living space to avoid overheating. Preferably masonry (like trombe wall).

12.Common wall vents: required as one of the ways heat is transferred to the living space. a. doorways, 15% of glazing areab. window openings, 20% of glazing areac. high and low vent pairs, 10% of glazing area

Thermal Storage RoofsThermal Storage Roofs Advantages:Advantages: Provides both Provides both heating and coolingheating and cooling

Provides low Provides low temperature swing temperature swing in the buildingin the building

Can provide 100% of Can provide 100% of heating and cooling heating and cooling in milder climatesin milder climates

Precautions:Precautions: Structural support Structural support for heavy mass for heavy mass expensiveexpensive

Most easily used in Most easily used in 1 story buildings1 story buildings

Typically 50% size Typically 50% size of floor areaof floor area

Least acceptable Least acceptable design in earthquake design in earthquake prone areasprone areas

Thermal Roof ConceptThermal Roof Concept

Passive Solar Design Passive Solar Design StyleStyle

The effectiveness of solar heating The effectiveness of solar heating does not depend on the style (Cape does not depend on the style (Cape Cod, Colonial, modern, Cod, Colonial, modern, contemporary) of house that you contemporary) of house that you design.design.

Houses may be small and simple, or Houses may be small and simple, or spectacular; the solar concept spectacular; the solar concept being applied is the same.being applied is the same.

Of course, the smaller the house, Of course, the smaller the house, the less resources and cost will be the less resources and cost will be needed to build and maintain it. needed to build and maintain it.

THANK U THANK U