Construction – Energy – Efficient Construction
The oil crisis of 1973-1974 exposed the delicate balance between the rising demand for energy and the Earth’s limited resources. Today energy-efficient construction is an essential, expanding area of building technology.
Land values can be a decisive factor in construction plans: high square-feet costs often lead developers to build taller structures for optimal economic returns. They then seek to balance above-average purchase, planning, and construction costs with reduced operational costs, although the building’s occupants expect a comfortable indoor environment throughout the building at all times. The result is a constant artificial climate within the building, with correspondingly high levels of energy use.
The main objective of en-ergy-efficient construction is to reduce these costs. This can be achieved in two ways: firstly, by taking advantage of cost-free energy sources whenever possible, and secondly, by using energy more efficiently or recapturing it. For this purpose, the building must be designed with measures to reduce its energy budget, including the use of alternative energy sources.
Another important consideration is minimizing energy loss: for instance, by optimizing insulation, using glass surfaces effectively, and installing efficient climate control, electrical, and water systems. Modern buildings often include automatic control systems for ventilation and sun protection, which provide a centrally managed, uniform climate within the whole building.
For in- creased energy efficiency, a decentralized control system can also be added. Increasing numbers of buildings are incorporating high-tech materials and techno-logical systems such as “smart” two-layer facades that react automatically to temperature and weather changes. Just as important, how-ever, are in-house energy production systems, such as solar collectors, photovoltaic panels, geothermal heaters, and waterrecycling mechanisms.
Measures such as these can be implemented both in new construction and in the renovation of older buildings, making them more energy efficient. Here, the ideal is the “energy-plus house,” which operates so efficiently that it produces more electricity than it uses. The excess can then be diverted into the local electrical system.
Over the long term, however, a number of problems still remain to be solved before energy-efficient systems for homes and buildings become common place: for instance, the high cost involved in manufacturing, managing, and repairing such technologically complex systems.
HEAT PUMPS
Heal pumps are capable of extracting heat from an area with a relatively low temperature, such as the ground, and moving it to an area of higher temperature, with the input of mechanical work: for in stance, from a pump or compressor.
This heat can then be used to warm a building, for example. Gases or liquids are used to help extract the heat. Compared to direct electrical heaters heat pumps consume less electricity
BASICS
CONVENTIONAL HOUSES require 25,360-95,100 Btu per square foot (80-300 kWh/m 2) for heating each year.
LOW-ENERGY HOUSES use less than 25,360 Btu per square feet (80 kWh/m2).
PASSIVE-ENERGY HOUSES need less than 4,750 Btu per square feet (15 kWh/m 2 ).
THREE-LITER HOUSES require only 3 liters (about 3 quarts) of oil or natural gas per year per square yard.
ENERGY-PLUS HOUSES produce more energy than they use. The surplus can be sold to the local energy utility.