Portugal legislated new efficiency Regulation on Heating, Ventilation and Air Conditioning (HVAC) Systems in Buildings in 2006, revising the national RSECE building code of 1998. Such revision complemented the Portuguese implementation of EU Directive 2002/91/CE on the Energy Performance of Buildings. The 2006 revisions establish strict standards for: - HVACs energy use; enumerating energy consumption limits in utilities of large buildings. - indoor air quality; assuring a reference indoor air renovation rate (legally fixed) and limiting the pollutant concentrations inside the buildings. - HVAC units design; limiting the installed power on HVAC systems and establishing a number of energy efficiency requirements on the design of new HVAC systems. - maintenance; mandating the performance of energy audits, every six years, to large utility buildings and of periodic inspections to boilers and air conditioning systems. Energy units and equipment must have preventive maintenance plans. Compliance with RSECE 2006 version is mandatory whenever a permit is requested for building a new or renovating an existing building. In addition to the above, the Regulations on Thermal Behaviour of Buildings (RCCTE) define the requirements for new residential and small service buildings without HVAC systems, namely in terms of wall and floor insulation, types of glass coverings and surfaces, limiting heat loss and controlling excessive solar gains. These regulations set limits on the energy requirements for air-conditioning and hot water production, making it compulsory to install solar energy systems and favouring the use of other renewable energy sources.