Passive housing

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A look at passive design principles. Useful resource for teachers of Construction Studies in Ireland.

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Passive housing

  1. 1. Passive HousingBarry Mattimoe 1
  2. 2. What is passive design? Passive solar design refers to the use of the sun’s energy for the heating and cooling of living spaces. In this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun. Passive systems are simple, have few moving parts, and require minimal maintenance and require no mechanical systems. (http://passivesolar.sustainablesources.com/)Barry Mattimoe 2
  3. 3. Passive Housing Principles Orientation/ layout Natural lighting Thermal mass Heating Airtightness Air quality GlazingBarry Mattimoe 3
  4. 4. Sun Path In Northern hemisphere nations the sun is positioned in the south. The sun rises in the east and goes down in the west. In summer the sun is higher in the sky than in winter (as shown in diagram)Barry Mattimoe 4
  5. 5. Orientation/Layout Note: Storage rooms placed As sun is in south, to provide to north side of house natural light the rooms that are busiest should be on the southerly façade of the home (kitchens, living area) Rooms which are used less frequently and need little lighting should be placed on northerly façade of home (utility, bathrooms etc.) Note: Living room, kitchen,Barry Mattimoe 5 dining room to south of house
  6. 6. Orientation/Layout As the sun rises in the east it is best practice to have bedrooms on the south east side of the home. This will provide light to the room in the morning when the sun rises.Barry Mattimoe 6
  7. 7. Natural lighting To provide natural light from the sun, large glazed areas are used to let the suns rays enter the home. To maximise the light from the sun, these large glazed areas should be on the south facing façade of the house. This will let the sunlight into the home Note: Larger overhang on roof to throughout the year. prevent overheating in summer months.Barry Mattimoe 7
  8. 8. Shading During the summer months there is a high chance of overheating in a passive home. This is due to the high levels of exposure to the sun. In order to combat this a large roof overhang can block the rays from the sun from entering the home. This overhang will prevent overheating during the summer and still allow all winter sun into the home.Barry Mattimoe 8
  9. 9. Thermal Mass Thermal mass is the ability of a material to store heat produced from sunlight. This concept is important in passive design as changes is temperature need to be controlled. Materials with good thermal mass store the heat from the sun and let it out slowly as the day progresses.Barry Mattimoe 9
  10. 10. Thermal Mass During the day the thermal mass materials absorb the heat from the sun. These materials release the heat slowly throughout the day and night. This keeps the house at comfortable temperature Good thermal mass materials: concrete, water, clay brick, natural rock/stoneBarry Mattimoe 10
  11. 11. Heating Solar heating panels can be used to provide hot water for the home. Panels are placed out southerly facing roof to absorb the heat from the sun throughout the year.Barry Mattimoe 11
  12. 12. How Solar Panels Work The solar panels are made of specially designed material that absorbs the suns rays extremely efficiently and when the sun heats the solar panels, a fluid is pumped from the hot water cylinder in your hot press up and around the solar panels. The fluid is then heated in the solar panels and returns to the hot water cylinder to heat the water in the cylinder.Barry Mattimoe 12
  13. 13. Airtightness An important aspect in passive design to prevent heat being lost in the home. All elements of the dwelling should have high levels of insulation to prevent heat loss.Barry Mattimoe 13
  14. 14. Wall Insulation In traditional building systems there is a chance of cold bridges in the wall area between small gaps at joints. As shown in the diagram warm air is being lost around the window and at the eaves. In passive homes this needs to be eliminated in order to trap all the heat in the house.Barry Mattimoe 14
  15. 15. External Wall Insulation Insulating walls externally is system suitable for passive homes. This system prevents any cold air from outside entering the building. It provides a full cover on the external surface of the building trapping in the heat inside the home.Barry Mattimoe 15
  16. 16. Viking Timber Frame Insulation Timber frame construction is suitable for passive design. Between the stud work of the timber frame it is packed with insulation. The insulation is packed in tight in between the studs to prevent any cold bridging. Insulation is usually 200- 300mm depending in thickness of wall.Barry Mattimoe 16
  17. 17. Roof Insulation Eaves ventilator insures ventilation in roof space to prevent timber rotting. This detail shows high levels of cellulose insulation which has been sprayed between the joists. The insulation goes down to eaves level and insures no cold air can travel through to the living area of the home.Barry Mattimoe 17
  18. 18. Roof Insulation This detail shows the insulation between the roof rafters. This system is used if the roof space is to be used as a living space. The insulation is rigid board and is cut to fit between the rafters of the roof.Barry Mattimoe 18
  19. 19. Foundation Fig 1 insulation Heat can be lost through the ground in a house. In traditional foundation systems there is a high Fig 2 chance of cold bridges coming from the earth into the house as shown in Fig 1. By using a modern insulated slab as shown in Fig 2 the bridge is prevented from occurring.Barry Mattimoe 19
  20. 20. Viking insulated slab In this foundation cold bridges are prevented. The foundation is insulated on the internal as well as external surfaces. The foundation is made up of polystyrene insulation which when joint forms a ring beam to which the concrete foundation is poured into.Barry Mattimoe 20
  21. 21. Air quality Indoor air quality is a important concern to take into account when designing a passive home. Due to the high level of insulation in passive homes, stale air can be trapped in the home if it is not released. This can lead to mould growing in the home and creating uncomfortable living conditionsBarry Mattimoe 21
  22. 22. Heat Recovery Ventilation (HRV) HRV units provide the clean air necessary to create comfortable living conditions. These systems take the stale air within the house out and let fresh air into the house.Barry Mattimoe 22
  23. 23. Heat Recovery Ventilation (HRV) Hot air from inside heats cool air When the hot stale air is coming into house in heat exchange extracted from the home, it core. is used to heat the cool fresh air coming in. The air from inside and outside pass through the same system however they never come in contact with one another. As the hot stale air leaves it heat the cool air coming in. this keeps the house at a comfortable living condition.Barry Mattimoe 23
  24. 24. Triple Glazing Note: Insulated window frame Triple glazed systems are often used in passive homes. Triple glazed systems have a high conservation of heat and also eliminate drafts in the house. The main disadvantage of this system is the distortion of light between the panes of glass.Barry Mattimoe 24
  25. 25. Double Glazing Don’t have as high thermal efficiency of the triple glazing system. However the double glazed system wont distort the light coming into the home to the same extent as the triple glazing system.Barry Mattimoe 25
  26. 26. Balance between glazing systems As both systems have good thermal efficiency it is suitable to use both types in the ne home. As the north facing façade will experience the cooler/stronger conditions it would be suitable to use triple glazing system on this façade. To the south/east/west facing façades it would be suitable to use the double glazing system as these sides of the home will take in the sunlight. This system wont distort the light as much as the triple glazing system .Barry Mattimoe 26

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