In Portugal, there is a critical need for architects to incorporate energy-conscious strategies on the process of refurbishment design. Passive design technology is still widely unknown or misused by Architects, to a large extent because information on these issues is scarce, mostly referring to foreign climatic and building contexts. There is also a great need for user-friendly tools, like the LT method, particularly for demonstrating and validating its use in the Portuguese context. This paper presents the LT-Portugal software, which is an energy design tool that can quickly assess the energy use (lighting, cooling, ventilation and heating) and thermal comfort implications of design options - both in existing projects and also to inform design decisions. Despite the complexity of the analysis, the LT method is easy to use and to apply to a range of situations. It is thus an ideal to assess refurbishment strategies, to which it has been applied before, and to make comparisons between various refurbishment options. (C) 2012 Elsevier Ltd. All rights reserved.