Module examines the basic principles of the energy chain: demand, supply, and distribution.
Course uses SI units to express values and data.
Initial reason for buildings was protection from weather. This is also why traditional buildings look so different in different climates.
Up to the 50s, HVAC systems were very limited so buildings had to be very adapted to the local climate.
Reduction of energy use to prevent climate change is one of the major challenges of our time. Buildings claim a significant amount of the total.
Energy use in buildings is determined by both the physical characterisitcs of the building and how it is used.
Almost every country in the world has policies for energy use in buildings. In Canada, the National Energy Code of Canada for Buildings 2011.
Most energy in buildings is used for a thermally comfortable indoor climate.
Energy and Greenhouse Gas Emission statistics in Canada.
The energy chain. The flow of energy between the demand side and supply side.
Consists for 4 main components. Supply side - natural resources needed to produce energy. Energy conversion process by which natural resources and converted to useful energy (electricity, heat, cold). Energy storage and distribution to buildings. Energy demand.
Supply side. Divided into 4 categories. 2 fossil fuels. 2 renewable. Combustible renewables -- converted to energy by being burned. Non-combustible renewables -- can be converted without being burned. Combustible fossil fuels. Non-combustible fossil fuels.
Primary energy. Important concept. Energy content of natural resources. Can be considered to be infinite for non-combustible renewables. Most important part is one connected to fossil fuels.
Conversion. May lead to harmful emissions. Various processes: buring, nuclear, hydrogen fuel cells, photovoltaic, wind, etc. Also emissions related to the "making" of the conversion process, e.g. building a power plant.
Distribution and storage. Depends a lot on the type of energy. Heat produced in a boiler must be distributed through piping. Electricity produced by PV must be stored in a battery or supplied to the grid.
Energy Demand. Influenced a lot by building demand. About the needs of the building.
Many policies and regulations address primary energy. National or local building codes address energy demand.
Final energy consumption: not completely consistent with energy chain. Economic and logistic based approach. Final energy use is the primary and non-primary resources provided to a buiding. Corresponds to the energy build.
Primary energy is essential when it comes to looking at environmental impact.
Design strategy to help make a building sustainable.
1. Reduce the need for resources. Note you can also reuse energy already in the building. Reduce waste heat.
2. Use infinite or renewable resources. e.g. wind or sun. Renewable sources are often intermittent.
3. Use fossil sources efficiently. Long term aim is to completely eliminate, but need them in the short term.
Energy chain: primary energy used to supply electricity, heat, cold, various fuels, to buildings.
Building concepts rely on this chain. But the building can also generate energy on site and use it or deliver it back to the grid.
"Smart grid", can add energy back to the grid if more is generated on site than needed. Biggest issue at moment is policy. Forbidden to export to the grid in many counties. Stability issues and existing monopolies.
Lots of different building concepts (passive, active, net zero energy, etc.)
Passive building: reduce energy demand as much as possible. Should be able to create comfort with almost no heating or cooling.
Active building: playing with control technology. If using infinite sources of energy, less need to reduce energy use. Attention is put on increasing use of renewables. Smart controls are used. Playing with energy market prices.
Net Zero Energy Building (NZEB): Balance of energy delivered to site and renewable produced and used on site. With only renewables there is a mismatch between supply and demand. Many types of this, not a standardized term.
Nearly Zero Energy Building (also NZEB): Small deviation of yearly balance is accepted. How large depends on national and local agreements (if any).
Positive Energy Building: More yearly on-site renewables than energy delivered to site.
In all of the above, fossil fuels are still consumed.
Zero Energy Building (ZEB): No fossil fuels. In some cases, can recieve off-site energy but must be renewable, other times all energy must be captured on site.
Carbon-Neutral Building (ZEB): No fossil fules.
Circular Buildings: lifecycle approach is used. How are materials processed before and after lifetime of building.
Healthy Buildings: concerned with not emitting harmful substances, incentives to exercise or eat healthy, etc.
Percentage of time spent indoors: ~90%
How to determine if a building is comfortable? Mostly depends on our senses.
Clothing. In office setting, you can't always wear whatever you prefer (e.g. forced to wear suits). Must take this into account in thermal comfort design.
Metabolic activity. e.g. busy cleaning will get hot faster than reading a book.
Air temperature. Can be different for different people. In bathroom might prefer 18 deg C, but 16 deg C when working out.
Radiation temperature. Temp of surfaces around you. Floor, walls, ceiling. Sitting next to a cold window will make you cold. A wall heated all day in the sun can give off heat in the evening.
Humidity. If too low, can get dry eyes and skin. If too high, causes mold, etc.
Air flows. Doesn't decrease indoor temperature, but can still make you feel more comfortable by making sweat evaporate faster. During winter, air flows are usually uncomfortable.
Air pollution. Not always detectable.
Light levels. Optimal is determined by activity and mood. e.g. candlelight dinner vs working. Morning vs evening. Artificial light and natural daylight are important.
Noise.
Comfort levels are complex. This course focuses on thermal comfort. This has the highest impact on energy demand. But as seen above, there are other factors. Thermal comfort is described in the ISO 7730 standard. Parameters of thermal comfort are clothing, metabolic activity, air temperature, radiation temperature, humidity, air flow.
From an energy point of view, its better to have different indoor temperatures in different times of the year. Also true for comfort.
For design purposes, assume acceptable range of 20-24 deg C indoors. 20 for cold season, 24 for hot. Be aware of local habits and regulations.