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Sustainable Design Part Three: The Basic Principles of Passive Design
 

Sustainable Design Part Three: The Basic Principles of Passive Design

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This presentation looks at the basic idea of passive design and how you can use the sun and wind to naturally heat, cool and light your buildings.

This presentation looks at the basic idea of passive design and how you can use the sun and wind to naturally heat, cool and light your buildings.

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  • This presentation, What is Sustainable Design? Part Three: The Basic Principles of Passive Design, is intended to provide an overview of the methods to be used to design buildings to minimize their need for fossil fuels and maximize their sustainable qualities.
  • In this presentation, we will discuss the basic principles of: Passive Heating Solar geometry Passive Cooling Wind and shading Daylighting Indirect lighting and materials issues
  • What is Passive Design? Passive design is: is based upon climate considerations attempts to control comfort (heating and cooling) without consuming fuels uses the orientation of the building to control heat gain and heat loss uses the shape of the building (plan, section) to control air flow uses materials to control heat maximizes use of free solar energy for heating and lighting maximizes use of free ventilation for cooling uses shade (natural or architectural) to control heat gain It attempts to use natural principles in order to substantially reduce dependence on fuel based technologies for heating, cooling and lighting the building.
  • How do Passive and Sustainable Relate? Passive solar heating and passive ventilation for cooling assist in creating sustainable building by reducing dependency on fossil fuels for heating and cooling buildings, as well as reducing the need for electricity to support lighting by using practices of daylighting in buildings. In LEED, Passive Design assists in gaining points in the Energy and Atmosphere category, as well as in Indoor Air Quality as Passive Design promotes natural ventilation and daylighting strategies. However, not all Sustainably Designed buildings are strongly Passive, and not all Passively Designed buildings are by default strongly sustainable (although this is more likely than the reverse.)
  • Passive Buildings Require Active Users Unlike most contemporarily designed buildings that rely on “Thermostat” control to regulate the temperature and relative humidity (comfort) in buildings, Passive Buildings require occupant involvement to ensure their success. Occupants need to be EDUCATED as to when to open and close windows, raise and lower shades, and otherwise control some of the non automated means of controlling the effects of the sun and wind on the interior environments of the building. Sometimes Passive Buildings, due to limitations in achieving an interior climate that falls in the middle of the “comfort zone”, will require occupants to accept a wider range of acceptable temperature and relative humidity values.
  • Differentiating Passive vs. Active Design Passive design results when a building is created and simply works “on its own”. The plan, section, materials selections and siting create a positive energy flow through the building and “save energy”. Active design uses equipment to modify the state of the building, create energy and comfort; ie. Fans, pumps, etc. Passive buildings require active users (to open and shut windows and blinds…)
  • Passive Means of Design The chart above outlines the basic passive strategies that can be used for climate control to reduce energy requirements. If we consider winter to be the heating season, we have to both promote solar gain and resist heat loss from our buildings. If we consider summer to be the cooling season, we have to both resist solar gain and promote heat loss – precisely the opposite of the winter condition. The sun, the wind, the earth and the atmosphere are used very naturally to achieve this.
  • Energy Reduction works with the tiered approach to design. Tier one asks that we get the basic building design to be climate responsive through basic design of the building itself. Tier two adds passive systems for heating and cooling. These will not work if the basic design is wrong. Tier three adds mechanical systems. If these cannot be very very small, they will not be able to be powered by the renewable energy available on or around the site. Traditional, contemporary building design STARTS with assuming that EVERYTHING will be powered with mechanically based systems.
  • Solar Geometry The study of solar geometry is essential to understanding how to both obtain free heat (passive heating) and reduce the amount of cooling through heat avoidance (passive cooling) on a building project. Solar angles vary in accordance with your position on the earth as well as the time of year.
  • Solar Position This diagram shows the angle that the rays of the sun make with the earth at Winter Solstice. The further the distance from the equator the more acute the angle. At 43 degrees north latitude the maximum height that the sun reaches in the sky at noon is around 21 degrees. This geometry also increases the distance that the sun’s rays must travel through the atmospheric layer that surrounds the earth. A lot of the energy of the sun is absorbed into the atmosphere, which is why the temperatures are also generally colder during these months, in addition to the daylight hours being decreased.
  • Solar Geometry Terms This diagram shows us the terms associated with solar geometry, in particular the relationship between declination angle, altitude angle and latitude. The latitude is a measure of your distance from the equator. The equatorial plane is set at 0 degrees. Solar Declination is a measure of how many degrees North (positive) or South (negative) of the equator that the sun is when viewed from the centre of the earth.  This varies from approximately +23.5 (North) in June to -23.5 (South) in December. This is shown as Theta in the diagram. The solar altitude is the vertical angle between the horizontal and the line connecting to the sun. This is shown as Beta in the diagram.
  • Why Solar Geometry? Understanding solar geometry is essential in order to: - do passive building design (for heating and cooling) - orient buildings properly - understand seasonal changes in the building and its surroundings - design shading devices - use the sun to animate our architecture The Perimeter Institute in Waterloo uses the sun to daylight and add character to the space.
  • In studying Solar Geometry we are going to figure out how to use the sun’s natural path in summer vs. winter to provide FREE heat in the Winter, and to reduce required COOLING in the summer. We need to understand how to manipulate the geometry over the time of day and seasons of the year so that we can properly design shading devices to keep unwanted sun and heat out of our buildings in the summer time, and allow the same into our buildings in the winter time.
  • Solar geometry works for us because the sun is naturally HIGH in the summer, making it easy to block the sun with shading devices. And it is naturally LOW in Winter, allowing the sun to penetrate below our shading devices and enter the building - with FREE heat.
  • Solar Transmission Through Glass: When sun strikes the glass part of the solar radiation is transmitted through the glass and proceeds to heat up the interior space. Part of the solar energy is reflected off of the glass. The amount is dependent on the angle of incidence. Part of the solar energy is absorbed into the glass, then reradiated both inwards and outwards. When looking to AVOID heat entering the building it is critical to prevent it from this initial transmission through the glass – as once the heat is in, it is IN.
  • Solar Transmission through Varying Types of Glass Different types of glass will transmit solar radiation differently. Residential and commercial glass type selection will be quite different. Residential buildings in cold climates are looking to allow heat in to use it for passive gain. Commercial buildings (with lots of interior loads from computers and equipment to offset) are normally looking to avoid heat gain. Clear glass allows the most heat transfer. There are very few iron oxide pigments in this type of glass to absorb the heat. Heat absorbing glass has different ingredients that initially absorb the solar radiation into the glass material itself, then radiate the heat later (more inwards than outwards). Reflective glasses are used on commercial buildings that wish to avoid heat. Much more of the solar energy is diverted from entering the building.
  • The Function of the Atmosphere: The atmosphere that surrounds the earth modifies the amount of solar radiation that is received to the earth’s surface and also assists in keeping the radiation/heat adjacent to the earth to create the constancy of our climate. The moon has no atmosphere and so has enormous temperature swings from day to night, as well as no breathable layer. Different sky conditions affect daylighting design. Daylighting prefers a diffuse sky condition – the kind you get when it is cloudy. Global warming is caused by the build up of greenhouse gasses in the layer of atmosphere, trapping the solar heat next to the earth. Very polluted cities have a greater than normal layer of particulates in their local atmosphere, making heating by solar radiation difficult. It is also more difficult for the radiation to reach photovoltaic panels as well as to keep those panels clean and optimally functioning.
  • Solar Energy as a Function of Orientation This chart demonstrates the variation in solar energy received on the different facades and roof of a building set at 42 degrees latitude. A horizontal window (skylight) receives 4 to 5 times more solar radiation than south window on June 21. East and West glazing collects almost 3 times the solar radiation of south window.
  • Types of Radiation The rays of the sun that carry solar energy can reach the interiors of our buildings through two primary means. Direct radiation is transmitted directly through the glass and carries with it the maximum heating benefit. Radiation can be reflected into the building either by bouncing off of light coloured surfaces on the ground around the buildings (like sand, light coloured concrete or snow), or it can bounce off of light coloured mateirals on the adjacent buildings. This can include light coloured stuccos, precast concrete or reflective glazing. Reflected light does not carry as much solar energy as some of the energy will have been absorbed into the initially struck surface. Reflected light is very useful when considering lighting a building with natural light, also known as daylighting.
  • The Geometry of Shading Devices When design to either allow or prevent solar penetration to the interior spaces, shading devices need to respond to the simple geometry of the sun to determine the length of the shading overhang. On low rise buildings that can be simply achieved by the roof overhand. On taller buildings, more elaborate devices must be incorporated.
  • Here we can see how a simple roof overhang acts as a shading device on the south side of the building. North facing glazing will only receive diffuse light for the majority of the year, and so no shading devices are required. When we design our elevations to be solar responsive, this will mean having different facade treatments to respond to sun angles and the degree of exposure of the facade.
  • Preventing Overheating Although the solar year is symmetrical about June 21 (summer solstice) the amount of solar radiation and therefore heat received is not. In the spring the weather tends to be cooler. There are no leaves on the trees to provide shade from the sun, but the earth has not yet warmed up. In August and September the sun angles are lower and there are leaves on the trees to provide some shade. But in many cases overhangs need to be designed to protect interior spaces from the sun at this time of the year as well. What this tells us is that we cannot use June 21 as the definitive angle for the length of the south facing solar shading device in a northern climate.
  • When designing south facing shading devices it is important to remember that the sun is not static. You cannot design the device to shade only at solar noon. It needs to function during the late morning and early afternoon hours as well. By simply extending the device either side of the window a better degree of shading can be achieved. It is sometimes more economical to gang the windows that to provide individual windows with individual shading devices.
  • Shading devices have to be designed to accommodate loads due to snow and ice, as well as sometimes allow rain to penetrate. You can either slope the shade or make it perforated to increase its ability to respond to weather loads. Perforated louvers also prevent the entrapment of heat in front of the windows.
  • Shading Strategies for East and West Orientations The simple overhang strategies for South facing windows do NOT work for East and West facades. The altitude angles of the sun are so low in the early morning and late afternoon, being near to horizontal, that they make long overhangs absolutely ineffective. There are alternate strategies that must be used for these orientations.
  • Dealing with East and West Facing Windows The best solution by far is to limit using east and especially west windows (as much as possible in hot climates) Next best solution is to have windows on the east and west façades face north or south The York University Computer Science Building uses a serrated façade that skews the west facing windows to face north – still providing light to the west façade.
  • Shading Strategies for East and West Elevations Or 3. Use Vertical Fins. Spacing is an issue, as well as fin length. It must be understood that if to be effective, they will severely restrict the view.
  • Shading Strategies for the North Elevation The sun also hits the façade from the north east and north west during the summer. Fins can be used to control this oblique light as well. It is a function of the latitude, window size and fin depth/frequency.
  • Living Awnings Living Awnings such as deciduous trees and trellises with deciduous vines are very good shading devices. They are in phase with the thermal year – gain and lose leaves in response to temperature changes.
  • Reduce Energy Loads: Passive Strategies The tiered approach to reducing energy requirements for HEATING begins with Tier 1, Maximize Heat Retention. In a northern climate this will include increases in the normal levels of insulation, providing thermal mass to store the heat, and making the building air tight to prevent losses through cracks. After we build an efficient building we can then use solar heating to heat the building. The heat will have thermal mass to be stored in and will have insulation and a leak free envelope to prevent losses. Mechanical heating can then be reduced to top off the amount that is not able to be supplied passively.
  • Passive Solar Heating Strategies There are 3 MAIN STRATEGIES used in building design to admit and store the free heat from the sun. These are: a. Direct Gain b. Thermal Storage Wall c. Sunspace The dominant architectural choice is Direct Gain as it clearly uses the windows to admit the sun and the materials inside the building to store the heat. In a Thermal Storage wall thermal mass is placed between the windows and the interior space to absorb the heat and allow for a slow transfer to the interior spaces. This precludes the use of the windows as vision glazing. In a sunspace (and this is not the same as a classic sun room or solarium) the space between the glass and thermal storage wall is enlarged to permit seasonal use of the space.
  • General Rules for Passive Solar Heating 1. Conservation Levels : Higher than normal levels of insulation and airtightness 2. Distribution of Solar Glazing : distributed throughout the building proportional to the heat loss of each zone 3. Orientation : Optimum within 5 degrees of true south 4. Glazing Tilt : Looking for perpendicular to sun angle in winter, although vertical efficient where lots of reflective snow cover 5. Number of glazing layers : 3 to 4 for severe climates, less otherwise 6. Night insulation and Low-E glazing : Greatly improves reduction of night heat losses 7. Mixing passive systems can increase comfort levels.
  • This space is using classic Direct Gain for heat. The sun shines through the windows. Strikes the exposed concrete floor. Heat is absorbed into the concrete as it is an excellent thermal mass. When the space cools off, the heat is radiated into the space making it warm. It is important to have enough thermal mass of adequate thickness to absorb the available heat from the sun. If the thermal mass is insufficient, then the heat will be absorbed by the occupants, who at 80% water, are an excellent source of thermal mass! It is also important to avoid floor coverings such as wood and carpet as these are insulating materials and will prevent the heat from being absorbed into, and reradiated from, the concrete. Staining the concrete can provide an attractive architectural finish.
  • These are cross sections of the space pictured on the previous slide. The sun heats the corridor space during the day and the openings between the space allow for heat transfer into the occupied office space behind. At night the openings are closed off to help the office space to retain the heat.
  • Reduce Loads: Passive Strategies The tiered approach to reducing energy requirements for COOLING starts at Tier 1 with Heat Avoidance. What you do not admit into the building you do not have to get rid of. Tier Two applies passive cooling. This will include using natural ventilation to get rid of unwanted heat and humidity as well as impact the choice of materials. Some materials can make the building and its occupants feel cooler. Tier Three uses Mechanical Cooling to make up the difference. Less mechanical cooling will be required if the loads are reduced through passive means.
  • What is Passive Cooling? As much as possible, passive cooling uses natural forces, energies, and heat sinks. Since the goal is to create thermal comfort during the summer (the over-heated period), we can either : cool the building by removing heat from the building by finding a heat sink raise the comfort zone sufficiently to include the high indoor temperature by increasing the air velocity so that the comfort zone shifts to higher temperatures.
  • Primary Passive Cooling Strategies Passive cooling relies on two primary strategies: 1. First and foremost, prevent heat from getting into the building ! If it does not come in, we don’t need to get rid of it. So - use shading devices - create a cool microclimate to discourage heat buildup. (This can be done by planting trees, shrubs and vines around the building. Avoid dark coloured pavement and finishes). 2. Get rid of unwanted heat that comes into the building - in cold and temperate climate, mainly via ventilative cooling
  • What is Ventilative Cooling? 1. Exhausting warm building air and replacing it with cooler outside air 2. Directing moving air across occupants’ skin to create convection and evaporation 3. Achieved by the wind , stack effect or fans. You have to not only provide openings but also, locate them correctly, make sure they are large enough, for this to work properly!!
  • Preventing Overheating in the Cooling Season Two main methods of preventing overheating: Prevent the sun from hitting the glass : This is done using roof overhangs, special shading devices or vegetation. OR 2. Use special glazing -- “Spectrally selective” glass filters the harmful rays out of the sunlight striking the glass. This is more expensive than regular glass used in windows.
  • Think Heat Avoidance This library has an enormous area of south facing glass that is not shaded and admits high levels of unwanted solar gain to the interior of the space. This design also causes high levels of glare for the occupants in the study carrols.
  • Vegetation can be used to shade the building and create a cool micro climate around the building.
  • Courtyard spaces can provide a cool semi private interior microclimate from which to draw cool air into the building.
  • Landscape and shading devices can be used in combination to provide an area of cooling around the building.
  • Reduce Energy Loads: Daylighting If we can light our interiors via daylight during the daytime hours, and also ensure that the lights are OFF when not in use, we can save a great deal of energy. The tiered approach to reducing energy requirements with DAYLIGHTING begins by making sure that the orientation and exposure of the building and openings in the façade will allow light to reach the maximum number of occupied spaces. Secondly we have to consider the colour, reflectivity and materiality of the materials in and around our buildings. Light coloured materials will work to bounce light and create for a light interior. Dark materials will absorb light and require more light to reach proper levels for the occupants to use the space. Lastly, we use energy efficient artificial lighting with occupancy and light level sensors to make sure that the lights are off when not required.
  • Daylighting does not equal sunlight! Daylighting is about bringing natural LIGHT into a space. Many daylit spaces do not WANT or NEED direct sunlight. Direct beam sunlight is about HEATING the space.
  • Differentiating Passive Solar Heating and Daylighting DIRECT SUNLIGHT is about FREE HEAT . DAYLIGHT (diffuse light) is about free LIGHT . Daylighting is environmentally advantageous because it: reduces the need for electric lighting therefore reducing the energy needed to power the lights reducing the heat generated from the lights thereby reducing the cooling required for the space
  • Daylighting concepts prefer diffuse or indirect lighting. With the proper use of shading devices to block direct sun penetration into the space, all exposures of the building can receive diffuse light rather than direct sunlight. It is necessary to differentiate strategies as a function of building use.
  • Light is an important architectural DESIGN TOOL. It has the ability to bring architecture to life. It relates to the use and cultural identity of the building.
  • Light can be use to reveal EXPERIENCE Seattle Public Library by Rem Koolhaas uses the contrast of light and shadow that is cast by the diagrid to create an exciting experience as you head towards the entrance.
  • Light can be use to reveal FORM Experience Music Project, Seattle by Frank Gehry Architect uses light to create a play of shadow on the curved forms and help to define the sculptural forms.
  • Light can be use to reveal SPACE British Museum Central Courtyard by Norman Foster uses the extreme brightness provided by the skylight and the light coloured stone materials to real the character of the space.
  • Light can be used to reveal MEANING The Pantheon in Rome relies on the light from the 20 foot oculus to wash the interior with a gentle, inspirational level of light.
  • It is important that you begin to really think about windows as architectural devices with the ability to provide buildings with heating and lighting, while at the same time, enabling a high level of innovation in design. There are large numbers of buildings that treat windows as patterning devices, and that do not take advantage of the sun in obvious ways. The windows in the Canadian War Museum ARE in fact, Morse Code – adding another purpose and level of meaning to the fenestrations.
  • The time of day will affect the reading of the window in the building. Windows look very different on the interior and exterior during the day and at night. These can be worked into special attributes if the reality is worked into the design. If improperly detailed, however, windows can serve as extreme leaks when it comes to the heating and cooling retention of your buildings.
  • In this presentation, we discussed the basic principles of: Passive Heating Solar geometry Passive Cooling Wind and shading Daylighting Indirect lighting and materials issues

Sustainable Design Part Three: The Basic Principles of Passive Design Sustainable Design Part Three: The Basic Principles of Passive Design Presentation Transcript

  • What is Sustainable Design? Part Three: The Basic Principles of Passive Design Terri Meyer Boake BES, BArch, MArch, LEED AP Associate Director School of Architecture University of Waterloo Past President of the Society of Building Science Educators Member OAA Committee on Sustainable Built Environment Aldo Leopold Centre, Barabou, Wisconsin – Carbon Neutral + LEED TM Platinum
  • Presentation Summary
    • In this presentation, we will discuss the basic principles of:
    • Passive Heating
      • Solar geometry
    • Passive Cooling
      • Wind and shading
    • Daylighting
      • Indirect lighting and materials issues
  • What is Passive Design?
    • is based upon climate considerations
    • attempts to control comfort (heating and cooling) without consuming fuels
    • uses the orientation of the building to control heat gain and heat loss
    • uses the shape of the building (plan, section) to control air flow
    • uses materials to control heat
    • maximizes use of free solar energy for heating and lighting
    • maximizes use of free ventilation for cooling
    • uses shade (natural or architectural) to control heat gain
  • How do Passive and Sustainable Relate?
    • Passive solar heating and passive ventilation for cooling assist in creating sustainable building by reducing dependency on fossil fuels for heating and cooling buildings, as well as reducing the need for electricity to support lighting by using practices of daylighting in buildings
    • In LEED, Passive Design assists in gaining points in the Energy and Atmosphere category, as well as in Indoor Air Quality as Passive Design promotes natural ventilation and daylighting strategies.
    • However, not all Sustainably Designed buildings are strongly Passive, and not all Passively Designed buildings are by default strongly sustainable (although this is more likely than the reverse.)
  • Passive Buildings Require Active Users
    • Unlike most contemporarily designed buildings that rely on “Thermostat” control to regulate the temperature and relative humidity (comfort) in buildings, Passive Buildings require occupant involvement to ensure their success.
    • Occupants need to be EDUCATED as to when to open and close windows, raise and lower shades, and otherwise control some of the non automated means of controlling the effects of the sun and wind on the interior environments of the building.
    • Sometimes Passive Buildings, due to limitations in achieving an interior climate that falls in the middle of the “comfort zone”, will require occupants to accept a wider range of acceptable temperature and relative humidity values.
  • Differentiating Passive vs. Active Design
    • Passive design results when a building is created and simply works “on its own”. The plan, section, materials selections and siting create a positive energy flow through the building and “save energy”.
    Active design uses equipment to modify the state of the building, create energy and comfort; ie. Fans, pumps, etc. Passive buildings require active users (to open and shut windows and blinds…)
  • Passive Means of Design
  • The Tiered Approach to Design Image: Norbert Lechner, “Heating, Cooling, Lighting”
  • Solar Geometry
  • Solar Position
  • Solar Geometry Terms
  • Understanding solar geometry is essential in order to: - do passive building design (for heating and cooling) - orient buildings properly - understand seasonal changes in the building and its surroundings - design shading devices - use the sun to animate our architecture Why Solar Geometry? The Perimeter Institute in Waterloo uses the sun to daylight and add character to the space.
  • In studying Solar Geometry we are going to figure out how to use the sun’s natural path in summer vs. winter to provide FREE heat in the Winter, and to reduce required COOLING in the summer. Terasen Gas, Surrey, BC Canmore Civic Centre, Canmore, AB
  • Solar geometry works for us because the sun is naturally HIGH in the summer, making it easy to block the sun with shading devices. And it is naturally LOW in Winter, allowing the sun to penetrate below our shading devices and enter the building - with FREE heat.
  • When sun strikes the glass part of the solar radiation is transmitted through the glass and proceeds to heat up the interior space. Part of the solar energy is reflected off of the glass. The amount is dependent on the angle of incidence. Part of the solar energy is absorbed into the glass, then reradiated both inwards and outwards. When looking to AVOID heat entering the building it is critical to prevent it from this initial transmission through the glass – as once the heat is in, it is IN. Solar Transmission Through Glass
  • Solar Transmission through Varying Types of Glass
  • The Function of the Atmosphere
  • This chart demonstrates the variation in solar energy received on the different facades and roof of a building set at 42 degrees latitude. A horizontal window (skylight) receives 4 to 5 times more solar radiation than south window on June 21. East and West glazing collects almost 3 times the solar radiation of south window. Solar Energy as a Function of Orientation
  • Since little winter heating can be expected from east and west windows, shading devices on those orientations can be designed purely on the basis of the summer requirement.
  • Reflective glazing Types of Radiation
  • The Geometry of Shading Devices
  • A simple roof overhang acts as a shading device.
  • Preventing Overheating
  • … extend device for full shading
  • The above two use louvres or grates that will let snow, rain and wind through. This one uses ceramic fritted glass that is sloped, to allow some light but shed rain and wet snow.
  • Shading Strategies for East and West Orientations
  • 1. The best solution by far is to limit using east and especially west windows (as much as possible in hot climates) 2. Next best solution is to have windows on the east and west façades face north or south Shading Strategies for East and West Elevations
  • 3. Use Vertical Fins. Spacing is an issue, as well as fin length. Must be understood that if to be effective, they will severely restrict the view. Shading Strategies for East and West Elevations
  • The sun also hits the façade from the north east and north west during the summer. Fins can be used to control this oblique light as well. It is a function of the latitude, window size and fin depth/frequency. Shading Strategies for the North Elevation
  • Living Awnings such as deciduous trees and trellises with deciduous vines are very good shading devices. They are in phase with the thermal year – gain and lose leaves in response to temperature changes. Living Awnings
  • Reduce Energy Loads: Passive Strategies The tiered approach to reducing energy requirements for HEATING : Maximize the amount of energy required for mechanical heating that comes from renewable sources. Source: Lechner. Heating, Cooling, Lighting. Tier 1 Tier 2 Tier 3 Maximize Heat Retention Passive Solar Heating Mechanical Heating
  • 3 MAIN STRATEGIES: a. Direct Gain b. Thermal Storage Wall c. Sunspace The dominant architectural choice is Direct Gain. Passive Solar Heating Strategies
  • 1. Conservation Levels : Higher than normal levels of insulation and airtightness 2. Distribution of Solar Glazing : distributed throughout the building proportional to the heat loss of each zone 3. Orientation : Optimum within 5 degrees of true south 4. Glazing Tilt : Looking for perpendicular to sun angle in winter, although vertical efficient where lots of reflective snow cover 5. Number of glazing layers : 3 to 4 for severe climates, less otherwise 6. Night insulation and Low-E glazing : Greatly improves reduction of night heat losses 7. Mixing passive systems can increase comfort levels. General Rules for Passive Solar Heating
  • This space is using classic Direct Gain for heat. The sun shines through the windows. Strikes the exposed concrete floor. Heat is absorbed into the concrete as it is an excellent thermal mass. When the space cools off, the heat is radiated into the space making it warm.
  • These are cross sections of the space pictured on the previous slide. The sun heats the corridor space during the day and the openings between the space allow for heat transfer into the occupied office space behind. At night the openings are closed off to help the office space to retain the heat. Aldo Leopold Centre, Barabou, Wisconsin
  • The tiered approach to reducing energy requirements for COOLING : Maximize the amount of energy required for mechanical cooling that comes from renewable sources. Source: Lechner. Heating, Cooling, Lighting. Tier 1 Tier 2 Tier 3 Heat Avoidance Passive Cooling Mechanical Cooling Reduce Energy Loads: Passive Strategies
    • As much as possible, passive cooling uses natural forces, energies, and heat sinks.
    • Since the goal is to create thermal comfort during the summer (the over-heated period), we can either :
    • cool the building by removing heat from the building by finding a heat sink
    • raise the comfort zone sufficiently to include the high indoor temperature by increasing the air velocity so that the comfort zone shifts to higher temperatures.
    What is Passive Cooling?
  • Passive cooling relies on two primary strategies: 1. First and foremost, prevent heat from getting into the building ! If it does not come in, we don’t need to get rid of it. - use shading devices - create a cool microclimate to discourage heat buildup 2. Get rid of unwanted heat that comes into the building - in cold and temperate climate, mainly via ventilative cooling Primary Passive Cooling Strategies
  • 1. Exhausting warm building air and replacing it with cooler outside air 2. Directing moving air across occupants’ skin to create convection and evaporation 3. Achieved by the wind , stack effect or fans. You have to not only provide openings but also, locate them correctly, make sure they are large enough, for this to work properly!! CHECK YOUR LOCAL WIND ROSE! What is Ventilative Cooling?
  • Two main methods of preventing overheating: 1. Prevent the sun from hitting the glass : done using roof overhangs, special shading devices or vegetation. OR 2. Use special glazing -- “spectrally selective” -- that filters the harmful rays out of the sunlight striking the glass. Preventing Overheating in the Cooling Season Terasen Gas, Surrey, BC
  • Salt Lake City Library, Moshe Safdie Think Heat Avoidance
  • Vegetation can be used to shade the building and create a cool micro climate around the building.
  • Courtyard spaces can provide a cool semi private interior microclimate from which to draw cool air into the building.
  • Landscape and shading devices can be used in combination to provide an area of cooling around the building.
  • Reduce Energy Loads: Daylighting
    • The tiered approach to reducing energy requirements with DAYLIGHTING :
    • Use energy efficient fixtures!
    • Maximize the amount of energy/electricity required for artificial lighting that comes from renewable sources.
    • Source: Lechner. Heating, Cooling, Lighting.
    Tier 1 Tier 2 Tier 3 Orientation and planning of building to allow light to reach maximum no. of spaces Glare, color, reflectivity and material concerns Efficient artificial Lighting w/ sensors
  • Daylighting does not equal sunlight! Daylighting is about bringing natural LIGHT into a space. Many daylit spaces do not WANT or NEED direct sunlight. Direct beam sunlight is about HEATING the space. Beijing National Theatre
    • Daylighting is environmentally advantageous because it:
    • reduces the need for electric lighting
    • therefore reducing the energy needed to power the lights
    • reducing the heat generated from the lights
    • thereby reducing the cooling required for the space
    DIRECT SUNLIGHT is about FREE HEAT . DAYLIGHT (diffuse light) is about free LIGHT . Differentiating Passive Solar Heating and Daylighting
  • Daylighting concepts prefer diffuse or indirect lighting. With the proper use of shading devices to block direct sun penetration into the space, all exposures of the building can receive diffuse light rather than direct sunlight. It is necessary to differentiate strategies as a function of building use.
  • Light is an important architectural DESIGN TOOL. It has the ability to bring architecture to life. It relates to the use and cultural identity of the building. City Centre, Las Vegas
  • Light can be use to reveal EXPERIENCE Seattle Public Library | Rem Koolhaas
  • Light can be use to reveal FORM EMP, Seattle | Frank Gehry Architect
  • Light can be use to reveal SPACE British Museum, Norman Foster
  • Light can be used to reveal MEANING The Pantheon, Rome
  • There are large numbers of buildings that treat windows as patterning devices, and that do not take advantage of the sun in obvious ways. In fact, the windows at the right ARE Morse Code.
  • Antoine Predock: Alumni Reception Hall, University of Minnesota … time of day affects windows...
  • Presentation Summary
    • In this presentation, we discussedthe basic principles of:
    • Passive Heating
      • Solar geometry
    • Passive Cooling
      • Wind and shading
    • Daylighting
      • Indirect lighting and materials issues