Although the Brazilian Federal Government has been increasing investments in the housing sector since 2004. there has been a significant increase in the housing deficit as well. In 2007 this deficit had already reached 7.2 million dwellings. The majority (84%) consists of families with monthly income under three minimum wages. However, none of the traditional lines of credit considers families up to that monthly income level for building their own dwellings. In 2004, a program was created to subsidize low-cost housing ("Programa de Subsidio A Habitacao de Interesse Social - PSH") with a maximum subsidy of about US$ 2500 for the construction of 'do-it-yourself' units. The present research had the general purpose of conceiving, constructing and evaluating the performance of a low-cost prototype consisting of wood and plywood panels. The object of analysis in this case study was a building prototype located in Canoinhas, in the South of Brazil (26 degrees 10'38 '' S, altitude 765 m above sea level), which was built within the scope of a program for subsidized low-cost housing. The present paper is concerned with evaluating the thermal performance of the finished prototype by means of onsite measurements and performing computer simulations for testing improvements of the original building prototype. From obtained results, general guidelines were drawn for improving indoor comfort conditions. (C) 2009 Elsevier Ltd. All rights reserved.