Embodied energy versus operational energy : showing the shortcomings of the energy performance building directive (EPBD)

Abstract

Energy is a key issue for Portugal, it is responsible for the higher part of its imports and since almost 30% of Portuguese energy is generated in power stations it is also responsible for high CO2 emissions. Between 1995 and 2005 Portuguese GNP rise 28%, however the imported energy in the same period increased 400%, from 1500 million to 5500 million dollars. As to the period between 2005 and 2007 the energy imports reach about 10,000 million dollars. Although recent and strong investments in renewable energy, Portugal continue to import energy and fossil fuels. This question is very relevant since a major part of the energy produced in Portugal is generated in power plants thus emitting greenhouse gases (GHGs). Therefore, investigations that could minimize energy use are needed.This paper presents a case study of a 97 apartment-type building (27.647 m2) located in Portugal,concerning both embodied energy as well as operational energy (heating, hot water, electricity). The operational energy was an average of 187,2 MJ/m2/yr and the embodied energy accounts for aprox. 2372 MJ/m2, representing just 25,3% of the former for a service life of 50 years. Since Portuguese energy efficiency building regulation made under the Energy Performance Building Directive (2002/91/EC-EPBD) will lead to a major decrease of operational energy this means that the energy required for the manufacturing of building materials could represent in a near future almost 400% of operational energy. Replacement up to 75% of Portland cement with mineral admixtures could allow energy savings needed to operate a very high efficient 97 apartment-type building during 50 years.