SUNDAY, FEB 5, 2023: NOTE TO FILE
Module 5-4
Conservation Strategies
· Insulation is one of the most critical building design details in order to mitigate the ingress of moisture and dampness into a building. There are many places in a building which are prone to dampness and should therefore be addressed through proper insulation as illustrated in Figure below.
General heat losses in a building (Source: http://www.city-architecture.co.uk/sustainable-architecture/heat-loss-diagram/)
· High performance windows are an important design feature considering the relative window to wall ratio and the density of glass to various walling solutions. The relatively low glass density makes for a greater transfer of temperature difference between the external and internal components of a building compared to most walling densities. However, with double or triple glazing with inert gas seals, the air gap reduces heat transfer by conduction (since air is a poor conductor) and convection (since the air gap is too narrow for convection currents). Furthermore, with Low-E, or low-emissivity glass, the amount of infrared and ultraviolet light that comes through glass is minimized without minimizing the amount of light that enters the building. Low-E glass windows have a microscopically thin coating, usually on the external face of the internal double glazing, which is transparent and reflects heat. The combination of double, triple glazing, Low-E glass and plant shading, all offers various combinations to reduce energy consumption of heating and cooling of buildings, as illustrated in Figure below.
Combination of double glazing and Low-E glass windows (Source: https://energyeducation.ca/encyclopedia/E-coating)
· Building materials is the choice of materials with low emergy (embodied energy / carbon footprint, both initial and ongoing – see Figure 5.14) as a means to reduce the ecological impact of a building by doing a life-cycle analysis (LCA). The LCA in this figure shows that, generally, the total emergy of a building, is approximately 35% during the initial implementation and 65% during the ongoing lifetime operational and maintenance of the building. One should therefore design to minimize the impact for both during and post implementation.
Life Cycle Analysis (LCA) – Embodied Energy (“Emergy”)
Given that many buildings exhibit high ecological footprints, it becomes imperative to reduce this impact through the choice of various building materials. Using local materials from within the bioregion of a building project will contribute significantly towards reducing emergy values, especially through relatively low emergy materials such as: local wood, unfired clay bricks, rammed earth, cob, adobe bricks, stone masonry, local ceramics and tiles, local insulation (which might be sheep’s wool, recycled paper, straw, hemp). See collage of “Building with Earth”.
Meanwhile, materials with high emergy include concrete, aluminium, steel, highly manufactured items, and, bulky materials sourced from great distances. The choice of building materials (Figure below) is therefore an important factor in designing for carbon neutral buildings.
Embodied carbon of some building materials
· Tight construction and ventilation are a feature of construction details which requires attention to detail to ensure air tightness where heating is necessary, which makes a large difference to the energy budget. However, it is also necessary to have forced air ventilation for bathrooms and kitchens. There are also useful techniques for passive or natural ventilation, as per the termite ventilation described before. The form and shape of a building is also an important factor to consider when detailing construction joints and ventilation. A typical useful software design tool that can identify potential weakness in building design is “Autodesk Ecotect Analysis, which is an environmental analysis tool that allows designers to simulate building performance from the earliest stages of conceptual design. It combines analysis functions with an interactive display that presents analytical results directly within the context of the building model”, as shown in the image below and in a short video demonstration.
Autodesk Ecotect software
· Natural lighting or daylighting is the efficient design to bring natural light into a building by using exterior glazing (such as, windows, skylights, etc.), thereby reducing artificial lighting requirements and saving energy, as illustrated in Figure below.
Illustration of natural lighting into a building. Source: https://riorenewables.com/efficient-design/natural-efficient-lighting)
3.4. Energy Strategies
This is covered in more detail in Module 4, but reference is made to the Figure below which illustrates a cyclical ecological design thinking for both new-build and retrofitting of buildings for energy conservation. Herein, several building systems are integrated in order to maximise sustainability of the building. More specifically, energy supply is from wind, solar thermal, photovoltaic, biogas; water supply from municipal source, but augmented with rainwater harvesting and wastewater treatment; and, an ecological sanitation system that recycles waste nutrients as compost and provides biomass for the biogas digestor. This ecological design reduces the negative waste impact and also the operational cost of utilities, such as, water, sewage, electricity and solid waste removal.
Whole systems thinking ecological design for new-build and retrofitting of buildings
Source: https://upload.wikimedia.org/wikipedia/commons/9/93/Floriade2012Design-GreenestBuildingNL.pdf
Module 5, lesson 5
