Efficient lighting in buildings: The lack of legislation in Portugal
Introduction
One of the sectors with higher preponderance on Portuguese energy consumption is the building sector, both in its residential and commercial components, as can be seen in the statistics of energy consumption published over past years. This is the case of the year 2009, more recent consolidated data, where energy consumption in buildings is 30% of total national consumption in final energy (DGEG, 2010) and approximately 60% of national electricity consumption (INE, 2011). A substantial portion of that energy consumption is electrical energy used to generate artificial lighting in commercial buildings. With this present concern, and to illustrate numerically the significance of lighting in energy consumption, it was possible to find a value for the rate of lighting energy consumption in the total electricity consumption of commercial buildings from the data published in the synthesis report “Caracterização Energética do Sector de Serviços” (DGE, 1994). Thus, energy consumption for lighting could be estimated at 29% of the total electricity consumption in commercial buildings for the year 1991. We present this value, although with reluctance for its antiquity, for the purpose of illustration of the difficulty in making an informed characterization with more recent data as it should be. The 29% figure is in line with the statistics for the nearby country of Spain that shows that for the year of 2010, 31.4% of electricity was consumed in lighting in commercial buildings (IDEA, 2011). Despite this difficulty, one can say without hesitation that lighting is one major consumer of electricity when analyzing energy consumption in the buildings sector. With reference to the above data, we can see the relevance of energy consumption of lighting and thus the available potential for energy savings. It is possible and desirable to add, in the new Portuguese law, directives that contribute to the improvement of buildings that are constructed in Portugal, characterized by its good performance in terms of availability of daylight, and at the same time, increasing the energy efficiency of lighting systems installed in those buildings.
Section snippets
Reference of the EU
Reducing levels of consumption for lighting in the building sector should be a concern for legislators taking them to put into law the necessary regulations to encourage the best available quality design, and construction, of residential and commercial buildings so they can make better use of daylight without forgetting or harming the thermal characteristics of those buildings. This concern is in consonance with what was defined as purpose and objective in various plans and programs produced
Portuguese legislation and European standards
As can be seen by the EPBD, the characteristics of positioning, orientation and construction of buildings are very important for its energy performance, and for this reason a field of action that the legislators should not forget. However, daylighting is almost nonexisting in Portuguese legislation. It shows a nearly complete regulatory uncertainty about the design and construction of buildings with the purpose of maximizing the use of daylight, and at the same time, increasing the visual
Situation in other countries
Traditionally, the legislations of several countries determined a minimum value for the area of openings in facades, typically 10% of the respective floor area. It is the case of Portuguese legislation for residential buildings. However, the major concern that originated with this measure was to promote the public health of the occupants of the buildings and, to a lesser degree, to promote the use of natural light in those buildings. The WFR of 10% is insufficient if we aim to partially replace
Efficient lighting, proposals
From the overall results of the analysis of the national situation with the lessons learned from the study of solutions in the legislation of other countries, we can conclude that it is possible and desirable to join some of the determinations and guidelines to the Portuguese law that are essential to ensure the construction of better buildings in our country, characterized by their optimum performance in terms of available light, natural and artificial, and by the efficiency of all the
Conclusions
Lighting in buildings has a relevance that, besides being intuitive, the share of energy consumption responsible can be recognized from the few known data. The few allusions to lighting in the legislation are, in most cases, statements with good intentions but without implementation of effective rules. This lack of specific regulations is not common in other countries. As we can see in the brief analysis of legislations of other countries presented in this paper, lighting is very much present
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