Active design strategies make use of bought energy like electricity and natural gas, to keep buildings comfortable. These strategies include mechanical systems such as air-conditioning, heat pumps, radiators, ventilators, and lighting. Active strategies also include renewable energy systems such as solar-electric and solar-thermal panels, wind turbines, and geothermal energy. Renewable energy is the powerhouse to achieve the goal of an energy-efficient building.
In areas where there is extensive sunshine, solar energy helps to generate electricity in several ways. One method is the solar chimney. Applicable primarily for desert locations, it consists of a tall column surrounded by a glass solar collector.
In effect, it is a chimney surrounded by a huge solar collector or greenhouse. The air is heated by the circular greenhouse and drawn through the chimney which acts as a thermal accelerator.
One of the most reliable systems is converting solar radiations into usable, photovoltaic (PV) cells. The material used for creating PV cells generate direct electrical current when exposed to light. The uniqueness of PV generation is that it has no moving parts and requires low maintenance. Silicon is, at the moment, the dominant PV material which is put on a suitable medium such as glass.
The disadvantage of PV cells is that with the current level of technology, they are expensive, capable of a relatively low output per unit of area, and only operate during daylight hours. Therefore, Photovoltaic generation is subject to instability in output due to seasonal variations. All in all, it has a long-term benefit, and also allows the user to return the surplus to the grid, hence earning monetary reimbursements.
Wind power is renewable energy obtained from the wind. It is the movement of air from high atmospheric pressure zones to nearby lower atmospheric pressure. To take advantage of wind energy through the rotation of the propellers, machines called wind turbines or mills are used for increasing the movement of the wind. The propellers are connected to a generator that raises the speed of rotation per minute, converting kinetic energy into electrical energy.
An example of successful integration of wind power and architecture is the Greenway Self Park, a partly self-powered parking garage in Chicago designed by HOK. The building houses vertical axis wind turbines stacked in a double-helical column along the windward corner, and its objective is to generate power to cover the cost of lighting the exteriors at night.
Biomass refers to the concept of using plant waste such as that obtained from managed woodlands or sawmills to generate energy. There are three ways to convert biomass and waste into energy:
Direct Combustion- It is a thermochemical technique in which the biomass is burnt in the open air or the presence of excess air. In this process, the photosynthetically stored chemical energy of the biomass converts into gases. Generally, Direct combustion uses a furnace, steam turbine, or boiler at a temperature range of 800–1000°C.
Biogas- It involves the tapping of methane produced by decaying waste material in landfill sites. This has a considerable environmental benefit since it burns the methane which would otherwise add more intensively to the greenhouse problem.
Liquid Fuel- The advantage of converting crops to liquid fuel is that it is portable and therefore suitable for vehicles. This is an alternative to using fossil fuels for the commute.
Geothermal Heat Exchange connects the building to the earth and takes advantage of the subterranean temperature to provide heating and cooling. The atmospheric temperature changes constantly with seasons.
Conversely, the same is not true for the underground temperature because of the insulating properties of the earth. Thus, Geothermal Energy capitalizes on these constant temperatures to gain “free” energy.
An HVAC system refers to mechanical systems for Heating, Ventilation & Air Conditioning to maintain the desired environmental comfort within a space.
Heat Recovery Ventilation (HRV) and Energy Recovery Ventilation (ERV) are dedicated ventilation systems that supply continuous fresh air. This process saves energy in heating and cooling of the space, resulting in lower energy bills and healthier indoor air.
Underfloor Heating uses conduction and convection energy of a heated fluid running through tubes into the floor and then to the occupied space. Advantages of this strategy includes lower energy consumption, a healthier indoor air value, and a higher level of comfort.
High-Efficiency Appliances that adhere to regulated targets for energy consumption can be applied inside the house to save energy during everyday chores.
Greywater is water that is used for showering, bathing, and hand-washing. It sometimes includes kitchen sinks and laundry wastewater.
This process involves the collection and treatment of this water for flushing, outdoor irrigation, and constructed wetlands, decreasing the overall demand for potable (drinkable) water. Drain Water Heat Recovery with Greywater Reuse will be beneficial for optimal energy and resource-efficiency.