What are the costs and benefits of bioclimatic architecture and passive systems?
There are many benefits of bioclimatic and energy conscious building design in general, such as: energy conservation, thermal/visual comfort, economic benefits (reduced fuel consumption, and cost of electromechanical equipment for heating – cooling – ventilation – lighting), environmental benefits (less pollution, reducing the greenhouse effect), social (improvement in the quality of life).
The largest amount of energy saving in buildings results from the proper and rational design, which includes appropriate orientation and layout of the building, the size, orientation and location of its openings, protection of the building envelope (insulation, protection from the wind and sun), and also from the rational operation of its systems. Effective solar control (shading) and natural ventilation in the summer are of key importance in reducing the energy demands of buildings.
It is preferable to have systems that are simple to build and operate and which combine thermal benefits throughout the whole year.
The amount of energy conservation through bioclimatic design varies depending on the type of building, the local climate and the particular technologies used. In houses in Greece, energy savings of around 15 to 40% have been recorded for heating and cooling requirements of the buildings in comparison to well constructed conventional buildings of the same age. In comparison to older buildings, the energy savings are even greater.
The application of bioclimatic design to new buildings does not increase the cost of construction, providing that simple systems and technologies are applied. If special technologies are used (i.e. solar walls or sunspaces), an increase of 10 – 15% in the cost of construction is considered reasonable. For retrofits of existing buildings, the cost is always higher. However, part of these costs can be incorporated into the overall building retrofitting cost.
How do I make a building bioclimatic?
For a building to be bioclimatic, it must be properly designed, with emphasis on suitable orientation, the arrangement of the internal spaces, provision for sufficient shading and ventilation in the summer. An architect, when informed about bioclimatic design principles, will be able to design a building of low energy consumption. The addition of indirect gain passive solar systems (solar walls, greenhouses) can provide additional energy conservation benefits. However, it is important that these systems are simple to use. For all passive solar systems and energy conservation techniques applied to a building to function, the involvement of the building user is necessary to some extent. This factor should be a basic criterion for the designers when selecting the systems and techniques which will be used, as in many cases, the complexity of the systems can result in lack of user involvement, which is necessary for the functioning of the building energy systems.
Of special significance during construction is the accurate application of the design, as minor modifications can have a significant impact on the thermal performance of the building. In most of the bioclimatic buildings in Greece, the deviation of the actual building construction from the original plan (construction errors and omissions) is the main reason for the reduced efficiency of passive systems. For example, a window designed to open, but built as inoperable, or a shading device not placed where it was supposed to, can result in considerable overheating of the building. If, instead of a solar wall in the building plan, an ordinary wall is built, there will be no solar gains as calculated in the plan and, therefore, no energy benefits.
The use of the building is equally important, as it can completely alter the energy performance foreseen. If, for example, a southern window is covered by curtains, it will not function as part of a solar system. If windows or skylights are not opened in the summer for night ventilation and are opened, instead, on hot days, or if the windows are not shaded, the building will overheat. If, on the other hand, during wintertime, the building is overventilated or air flows through cracks, the building will not be warm enough. If electrical appliances are used thoughtlessly, or if instead of using ceiling fans air conditioners are used, excessive energy will be consumed for cooling, with all the resulting economic and environmental consequences.
For buildings of the tertiary sector (offices, commercial spaces, hotels, etc), the efficient operation of passive systems and other energy systems often requires the installation of automation and control systems as it is difficult to involve the user in the operation process.
A final parameter in ensuring the optimal functioning of bioclimatic buildings and in reducing the problems which are created over time is the maintenance of the building and its systems.
My home isn’t bioclimatic. What can I do to improve it?
In order to improve the energy efficiency of a building, there are three types of actions that can be taken:
Large scale improvements which can occur during a complete renovation. Examples are the replacement of windows (with double glazing and insulating frames), addition of insulation or of passive systems on the exterior of the building, or converting parts of the structure into passive solar (i.e. the conversion of an ordinary wall to a solar wall), addition of external shading devices (fixed or movable, etc.)
Small scale, low cost repairs, such as sealing cracks, adding interior movable shades (such as Venetian blinds), installing ceiling fans, using plants for shade, replacing incandescent light bulbs with energy efficient ones, etc.
Non technical measures, such as ensuring the rational operation of the building and its systems, such as by correct use of windows (for sun penetration during the winter, shading and night ventilation during the summer), and rational use of appliances so as not to place a heat burden on the building (for example, not cooking during the hottest part of the day).