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Summary of Sustainable buildings (7LS3M0)
Clear and concise summary of the complete course.
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Summary Sustainable building/Physical aspects of building materials (7LS3M0)Lecture 1 Sustainable Building
Sustainableenvironmental friendly, durableexists for a long period, a building that is durable is
also sustainable. Dimensions of sustainability: ecological (human health/ecosystem/natural
recourses, planet), economic (profit), social (people)
Sustainable implies no:
1. Pollution
- 3 sources of pollution are: air, water, soil (+groundwater). U.S. environmental
protection agency (1970), analysis of contaminants, prevention of pollution. Air and
water is becoming cleaner over the years due to stricter restrictions
2. Depletion of resources
- 4 sources of depletion: land (scape), water, (air) (pollution can also cause depletion),
energy (non-renewables), raw materials. Ecosystems and landscape are indirectly
affected by depletion.
- Movements: action programs, laws, regulations, new culture
- The predictions for oil were not true, more reserves are found (due to technological
development), reserves economically exploitable (market price), efficient use of oil (do
more with lessephemeralisation), more re-use and recycling (for materials)
3. Physical (environmental/biological) disruption
- Loss of land (mining, building, landfill)
- Soil erosion (bigger problem than oil, soil important for food production)
- Loss of biodiversity (ecosystem, species and genetic diversity)
- Noise/light
4. Social/cultural disruption
- Communication
- Transport/work/recreation
- Relations between people
- Esthetics and visual impact
Global growth (economic growth, urbanization)bigger demand, so sustainable buildings needed,
most people live near water
Ecological footprint: we have enough resources when we use it/increase efficiently, recycling of
materials is important. Important to keep materials in their own cycle. And ephemeralizationdo
more with less
Sustainable: no pollution or depletion
Depletion of non-renewable materials (fossil fuels) may be larger than expected, minimizing
consumption by: prevention, re-use, recycling, no waste
In the building sector:
- Sources of depletion: energy, water, transport, materials, space
- 50/60% of worldwide energy consumption, it is more in reality due to indirect use
(embodied in materials), direct (HVAC), infrastructure indirect (moving of people due to
infrastructure). Embodied: excavation, transport, production/process, transport
- Global production of building materials from most to least: concrete, cement, timber,
asphalt, steel, plastics, gypsum, quicklime, bitumen
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, - Building materials: Cement and bitumen (e.g. black layer on top of roofs) are binding
materials, cement is a component of concrete
- When you are replacing fossil fuels (e.g. hard coal, oil, natural gas) with renewables
(timber, grain, oilseed) you also affect the food production
- Embodied energy (energy in the materials), most energy in plastics and steel (from scrap
closer to 9, when you have all the processing step closer to 22). Place of production also
affects the embodied energy, due to transport. For drying the material heat/energy is
needed.
Role of building codes: safety (structural, fire, user health, nature and crime), minimum standards
(durability of materials against weather, and sustainability e.g. reducing water and energy use). First
building code regulated structural safety, now sustainable buildings is a moving target.
Environmental considerations: look at the whole life cycle of a material, concrete (non-renewable,
but you can store energy in it which makes a building energy efficient, less maintenance needed).
Timber is a renewable material (wind turbines from timber). Aluminum: corrosion resistant, tensile
stress, low maintenance , but “red mud”pollution and waste during production of a material
LCA life-cycle assessment:
- Integral evaluation: pollution, waste, depletion, land, energy, water, transport, material
- Service lifetime
- Look at:
o Raw materials: extraction, processing, transport
o Products: production, transport, distribution
o Application: use, maintenance, resuse
o End of life: recycling, disposal
- Used for products and objects
- Qualitative and quantitative tools for ranking materials (GPR, eco-quantum, greencalc+)
Triad approach when you develop a building is used for the aspects: energy (trias energetica), water
(trias hydrica), materials (trias hylica), space (trias toponoma), transport (poreutica). Triad approach:
1. Prevention (reduction of demand)
2. Deploy renewable sources
3. Deploy non-renewable resources efficiently
Example for energy:
1. Energy saving measures
2. Sustainable energy sources
3. Efficient use of fossil fuels
Instead of thinking in a linear process we should think in a circular process (zero waste and
pollution)
In design phase: design for re-use, disassembly, recycling, biodegradation
How to achieve sustainable buildings: no pollution, reduce demand, re-use existing stocks, deploy
renewables
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,Lecture 2 Trias Energetica (focus on energy)
Heat (J) is thermal energy, heat flow Q (J/s or W), flows from high to low temp. Materials possess
density, heat capacity, and conductivity. All substances exist in three phases, gas, liquid, and solid.
We want to control temperature, humidity, sound level, illuminance
- Temperature: heating is needed for comfort, max indoor temp 28 degrees, yearly average
outdoor 9.5 degrees. Heating is needed, often done with gas. In commercial/public real
estate cooling is needed due to internal heat generation
- Highest gas consumption for detached house, lowest for apartment
Historical overview heat in buildings:
- shelter and fire, single layer walls
- Twenties: inner and outer envelope
- Seventies: entral heating system (no coal anymore) (efficiency 50%), double glazing
- Eighties: high efficiency boilers
- Nineties: triple glazing
- Now: energy neutral, heat pumps, zero-energy
A building is not a closed system, air is coming in and going out, same for energy.
- Electric energy comes in
- Fossil fuel and solar irradiation (sunlight) come in, metabolism (from people/animals)
- Heat will flow out
Heating is needed for comfort. Ventilation is needed for many reasons e.g. comfort and health
Heat transfer/transport in 3 ways: conduction, convection, radiation
Floor heating: convection and conduction, fire place: radiation. Heating system: generation,
transport, distribution, delivery. Medium: water or air.
Heat is stored in building materials, water/ice
Trias energetica:
1. Energy saving measures
2. Sustainable energy sources
3. Efficient use of fossil fuels
Prevention of energy use (step 1):
- Ventilation (planned exchange of air), best to use balanced ventilation to prevent heat loss
o Ventilation factors: volume of air, movement of air (not too fast), distribution of air,
filtration, temperature change, humidity change, feedback and control, energy use
that drives the system
o Two types of ventilation: mixing & displacement
o Natural ventilation is provided by two mechanisms:
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, Air pressure differences
Stack effect: creation of pressure difference (higher chimney higher delta P),
natural draft created. Windcatcher: wind creates pressure difference which
drives air
o Solar chimney: extra stimulation by glass, air is heated and pressure differences
become higher
o Convective energy loss:
o Balanced ventilation: precooling incoming air with heat from outgoing air, uses heat
wheel/recuperator LBK
- Try to avoid infiltration (not planned exchange of air)
o Related to air tightness, occurs where part of the construction come together (roof,
door, window)
o Avoid infiltration to prevent heat loss
- Building envelope area/volume (compactness of building)
- Insulation
o Resistance R (m2*K/W, d/lambda), transmittance U (W/m2*K), thermal bridging f-
factor. Thermal conductivity of insulator aerogel lower that air
o Floor and roof often better insulated than walls
o U value of windows is including glass and frame
o Green roof, layer of soil and contains water, so good insulation layer
o F-factor thermal bridges: Twall lowest-Tout/Tin-Tout, should be bigger than 0.65
- Heat capacity, heat buffering capacity by using the thermal mass of a building
o Balances ventilation
o Thermal mass can buffer a day cycle, a year cycle can be buffered by an aquifer
o Water can also be used for thermal storage, low specific heat
o Heavy mass means less temperature variations inside
- Most gains can be achieved in existing buildings, they must be improved
Materials affect energy via: embodied energy, thermal conduction, reflection/absorption,
infiltration, heat buffering capacity (due to specific heat)
Heat gains:
- People (metabolism), computers, lighting, solar energy by wall and windows
- Renewable energy sources:
o Solar energy:
Fossil fuels are stored solar energy
Passive: orientation of house, active: solar collector/PV panelsin
combination with green roofs, the green can help cooling the PV panels
which improves the operation of the panels
Via windows, g-value is the percentage of heat that passes through the glass
(lower is better)
- Heat generation/delivery:
o Efficient boiler system: natural gas is needed, improved boilers (100% of gas heat is
used to heat the water, there almost no heat in the gas when it leaves the chimney
for this reason a ventilator is used)
o Fuel cells: electrochemical energy is converted directly to electric energy
o Combined heat and power/cogeneration: gas is used to generate electricity, waste
heat used
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