By David A. Bainbridge
The Greek writer Aeschylus described the barbarians, “Though they had eyes to see, they saw to no avail; they had ears, but understood not. They lacked the knowledge of houses…. turned to face the sun…”
The basics of climatically adapted design have been known since Greek and Roman times. They have been studiously ignored by architectural schools, architects and engineers, LEED and building codes; but the rising cost of energy is encouraging reconsideration of these smart design features. Climatically adapted design can improve comfort, security, and productivity and dramatically reduce the cost of operation. It can also reduce construction cost.
The best orientation is usually for a building to be longer east-west that it is north-south, with a major wall the equator, many of the windows facing the equator, and few facing east or west. This orientation will maximize solar heating in winter and minimize summer overheating by making best use of the seasonal difference in sun path. This was well understood in Ancient Greece and Rome where houses were solar oriented, some cities were laid out for good solar access and where legal action could be brought to maintain solar access to keep a home warm in winter.
The second step in building or remodeling for energy efficiency is reducing unwanted conductive and convective heat loss (or gain). Most homes and commercial buildings are under-insulated and leaky. More insulation and better weatherization can improve efficiency and provide controlled ventilation so that fresh air comes in when and where you want it. With a good building shell we can apply the following design principles for a naturally heated and cooled, ventilated and daylit building where people will be dancing in the sunlight.
5 Rules for Low Cost Natural Heating
1. Make sure the building shell is very well insulated and weathertight.
2. Orient the building properly, with windows on the equator facing side. A rectangular shape that is wider east-west than north-south is best in most climates.
3. Use the minimum amount of equator facing window area needed for heating (often only 5-8% of floor area).
4. Include high performance windows with insulated shades or shutters in winter. Use high solar heat gain glazing on the equator facing windows.
5. Use the simplest, smallest, and most economical method of providing needed thermal mass. This will often be doubled sheet rock in south rooms, thicker plaster, concrete or tile floors and water tanks.
5 Rules for Natural Cooling
1. Make sure the building is oriented properly with most windows on south and north, few on east and west.
2. Provide shading for all windows in summer (awnings, overhangs, etc.). 3. Use light roof colors and light wall colors.
3. Choose and place windows and vents for good ventilation and convective cooling. Use paddle fans for air circulation, use night ventilation (consider a whole house fan) if night air temperatures are low.
4. Use thermal mass (water tanks, doubled sheet rock, plaster, rock, tile or concrete) to store nighttime coolth for use during the day.
5. Use landscaping to cool the building environment.
5 rules for effective ventilation
1. Consider wind direction, speed and temperature in window type and orientation of openings and the design of interior spaces and connections. Undercut doors, use transom vents, or use open plans to provide good ventilation.
2. Embrace stack ventilation, by adding roof monitors or high and low vents.
3. Consider dust and allergen issues and install filters to reduce problems.
4. Consider security, so open windows to not compromise safety and security.
5. Add mechanical ventilation as needed with optimized efficiency ceiling fans and vents.
5 rules for effective daylighting
1. Orient the building properly, integrate windows in daylighting design.
2. Use exterior light shelves to bounce light onto ceilings from higher windows.
3. Use interior diffusers to soften and reflect light when exterior light shelves cannot be used.
4. Use roof monitors, clerestory windows and solar tubes for daylighting interior spaces.
5. Use courtyards, transparent or translucent interior doors, walls and windows to allow light into the building core.
These rules work together to make buildings more pleasant and healthful to live and work in. A well designed naturally heated and cooled building can reduce energy demand for heating and cooling from 80-90%. This was first demonstrated in the 1960s, perfected in the 1970s and 80s and implemented by the German’s in the 1990s in the growing passivhaus movement. The ING Bank building in Amsterdam demonstrated that these savings can be achieved by large buildings as well as homes. If climatically adapted, solar design is correctly integrated in buildings we can improve comfort for one tenth the energy commonly used today. For retrofits we can expect savings of 50-70% If we count productivity gains and reduced absenteeism (usually 10-15%) passive solar doesn’t cost at all – it pays.
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