Understanding building design, resource flows, inputs, outputs and activities

A. Useful web sites to consult 1. UNIDO, “Energy Efficiency in Buildings,” http://www.unido.org/fileadmin/import/83276_Module19.pdf2. Nordic Folkecenter, “Energy Efficiency of Buildings and Renewable Energy, http://www.folkecenter.net/mediafiles/folkecenter/pdf/Energy_saving_in_buildings.pdf B. Critical concepts to address 1. The building as an ecosystem: A building should be regarded as a mini ecosystem. People & other living things, resources, materials go into its construction and operation, various “functions” take place inside, which use external inputs, and people, heat, and wastes come out. The diagrams below illustrate this. Task: Make a list of other things going in and out.

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2. Energy moves in mysterious ways: Energy and heat move into, out of and through the building. There are three forms of heat movement/transfer: convection (airflow via ducts, across spaces, in and out of holes in the envelope), radiation (infrared emissions through windows & from surfaces of heating elements, lights, bodies), conduction (heat transfer through materials from warmer to cooler spaces, thermal storage & solar gain). Lighting and waste heat from computers, etc. can also be a significant source of heat.

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3. Building envelope: The “containment structure” through which stuff enters and exists; made of various materials and designed with “holes” throughout. Building materials include brick (not on the California coast), wood, stucco, iron & steel, plastic, fiberglass, glass, aluminum, water, heating, ventilation pipes & shafts, electrical & communication lines and shafts, lighting. Task: Try to identify envelope materials and “holes” in the building you are in.

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4. Building energy: The energy that enters a building and the waste heat that leaves it comes from a variety of sources, some deliberately installed (e.g., heating, lighting), others that arise from design features (e.g. windows, holes in the envelope). The temperature inside a building is a function of heat flows into or out of the building (and this includes occupancy). To do a complete energy survey of a building, one should take all of these features into account.

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5. Calculating thermal capacities of a building: All materials used in building possess an intrinsic resistance to heat flow. Some, such as single pane glass, allow heat and radiation to pass through easily (although glass does offer resistance to heat flows; consider a greenhouse). Others, such as insulation, are designed with internal air spaces to limit conduction as a form of heat transfer. Resistance is measured as “R-value” (per inch of material thickness); transmissivity as “U-value.” Some materials hold heat for long periods, including water and various types of stone and concrete. A “Heating degree day” (HDD) is a measure of cold weather: the average daily temperature (usually per month) in a location minus 32° F times the number of days in the period of time equals HDDs. One can also calculate “cooling degree days”

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6. Building Resource systems: These consist of mechanical and other systems that bring resources into the building and take out waste products: heating/cooling (steam, hot air, electrical resistance, air conditioning), water and sewage, electricity, natural gas, food and garbage. All but the smallest buildings have heating and cooling as well as ventilation systems. Total efficiency depends on what is being “burned” (oil, natural gas, coal, wood, solar hot water), where generation and use are taking place (oil refinery, power plant, furnace, electric heater), and the efficiency of each step. Air conditioning is like refrigeration—it involves using liquids and gases to capture and transfer heat, either to the outside, a water source, or into the ground. Heat pumps can extract heat energy or “coolth” from the ground. Task: Locate these systems in your building.

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7. Lighting: Electric lights and windows are both important sources of lighting. There are usually standards for required lighting levels in commercial buildings, and most houses are designed with at least some minimum in mind. A typical incandescent bulb (60-100 watts) emits most of its radiation as heat, and its efficiency is very low (2%). A compact fluorescent bulb consumes much less (5-20 watts) and are more efficient in terms of energy use (7-9%), light output (3-4x) and (theoretically) much longer lifetimes. LED lights can be even more efficient (1.5-13%) with as much as 6x the light output and very long lifetimes.

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8. Appliances & other resource-consuming devices: These have already been addressed to some degree, but the number and variety of powered and resource using devices in any building will have a considerable effect on flows in and out, as well as internal conditions (some of which work against each other). Task: Compile a list of appliances in your home.

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9. Moisture and air quality: An important consideration in terms of energy and resource use has to do with the environmental conditions inside a building. In general, we can control for temperature rather easily, but the introduction of moisture and the general air quality must also be considered. Moisture is generated as a result of condensation on poorly-insulated surfaces (e.g., windows, thin metal surfaces), evaporation from internal water sources in locations such as kitchens and bathrooms, and from energy sources such as burning wood and natural gas. Too much moisture in specific locations can contribute to mold, mildew and dry rot. Air quality is affected by radioactive elements in building materials, soil and water, emissions from burning natural gas, outgassing from materials, carpets, paints, and smoke from various sources. A building that is too well-sealed against convection losses can suffer from excessive moisture and low air quality.

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10. There are many other inputs, outputs and flows to consider: food, people, clothing and fabrics, furniture, wall and floor coverings, paint, chemicals, paper products, bacteria and germs, people and pets. All of these are part of the building ecosystem and make contributions to resource and energy use, and waste and heat outputs. Full consideration of the building ecosystem requires that these be taken into account. Group activity: design a conceptual flowchart for a Santa Cruz household.

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