Buildings take part in the GHG emissions and in energy consumption. In 2010 buildings meant a 32% of total global final energy use and a 19% of energy‐related GHG emissions (approximately one‐third of black carbon emissions).
The building envelope is the boundary between the conditioned interior of a building and the outdoors. Building components like external walls, floors and roofs are important to determine the amount of energy that is required for heating or cooling the building.
Heating and cooling the buildings by means of the envelope of the building, can save around 30% of the energy consumption, rising to 50%-60% in cold climates.
There are appliances which are energy-efficient. They are able to save up to $400 per year. New appliances (washers, dishwashers, air conditioner…) use less energy than the old ones. For example, new clothes washers use 70% less energy and new air conditioners use 50% less energy. If we do not need to buy a new appliance, we can use the existing appliances more efficiently so that we can extend the working life of them. If each of us increases the energy-efficiency in out appliances by 30%, we will release the demand for electricity by the equivalent of 25 power plants.
If all homes in Europe changed their more than ten-year-old appliances into new ones, 20 billion kWh of electricity would be saved annually, reducing CO2 emissions by almost 18 billion kg. The energy required by an appliance depends on the moment of the day. For example, an air conditioner uses more energy during the afternoon when it is hot than during the night.
Lighting is about 15% of an average house’s electricity use. If we want to achieve a more energy-efficient lighting, bulbs have to be replaced by compact fluorescent light bulbs (CFLs) or light emitting diodes (LEDs). Incandescent bulbs are based on old technology and waste 90% of their energy as heat. Compact fluorescent light bulbs are the cheapest and the most effective choice in lighting. A CFL produces the same amount of light than a conventional bulb (incandescent bulb) but it uses 75% less energy, produces75% less heat, and lasts up to 10 times longer than incandescent bulbs. These bulbs contain mercury so we have to recycle them at the end of their life period.
LEDs are more efficient and provide higher quality than CFLs. LEDs use roughly 75 percent less energy than incandescent bulbs, emit no heat, and last 25 times longer. LEDs use light emitting diodes to produce light very efficiently.
Adoption of LED lighting could:
REDUCING DEMAND OF HVAC SYSTEMS
Reducing demand of these systems is important and it can be achieved by means of different methods such as improved insulation, window glazing, natural ventilation and painting roofs white (which reduce air-conditioning loads by 20%). Optimising building design, assessing cool roof application, reducing heat generation from lighting and optimising temperature and humidity to save energy are ways to reduce the demand of HVAC systems.
UPGRADING HVAC SYSTEMS
•Installing HVAC systems in milder climates can achieve electricity savings.
• Using more efficient technologies: according to the IPCC modern technologies can enable reductions in HVAC systems demand of at least 50%. In this way, buildings can use smaller HVAC systems and consume less energy and water. Some of these technologies are radiant chilled beams, displacement ventilation and climate control.
The warmer air has a lower density than the cool air, and thus creates convective flows known as thermal plumes. The warm air then leaves the zone at the ceiling height of the room. Diffusers can be located against a wall, at the corner of a room, or above the floor. Displacement ventilation can be coupled with other cooling and heating sources, such as radiant chilled ceilings or baseboard heating.