R. Sousa 1, H. Sousa 1, L. Silva 2, I. Flores-Colen 3 and M. Pedroso 3
1)  CONSTRUCT – Faculty of Engineering University of Porto
Rua Dr. Roberto Frias, s/n 4200-465 Porto (Portugal)
e-mail: ruysousa@fe.up.pt
2)   Saint-Gobain Weber
Zona Industrial da Taboeira – Esgueira, 3800-055 Aveiro (Portugal)
e-mail: Luis.Silva@saint-gobain.com
3)   CERIS/DECivil, Instituto Superior Técnico, Universidade de Lisboa
Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
e-mail: {ines.flores.colen, marco.pedroso}@tecnico.ulisboa.pt

Keywords: Thermal improvements, wall system, masonry, thermal render, lightweight materials.

Abstract. This paper presents the main aspects regarding the development of a sustainable and energy-efficient external wall system. This development is ongoing under the scope of a national funded research project with the construction industry. One of the main objectives was to develop a lightweight masonry and an external render with improved thermal behaviour and enough mechanical strength to be used in infill/non-structural walls. It was assumed a maximum gross thickness of 25cm for the masonry wall and 5,5cm for the rendering layer. The masonry being develop is made with a perforated lightweight concrete unit/block, thermally improved through topology/shape optimization and by the use of open structure lightweight concrete (LWC) with lower thermal conductivity and sufficient mechanical strength. The rendering system is made with a lightweight cement based render, thermally improved with lower thermal conductivity base materials/aggregates. The thermal and mechanical behaviour aspects related to the numerical simulations, experimental testing performed and results obtained in the scope of the research project are presented and discussed, highlighting the mechanical and thermal optimization/characterization of the thermal render, LWC units and masonry, including development aspects of their base materials (LWC and render mixtures). Generally, the results obtained are in good agreement with main objectives of the project.