Economic, ecological and thermo-hygric optimization of a vapor-open envelope for subtropical climates
Journal article, 2012

With regard to resource depletion and global climate change, it is becoming important to take holistic measures comprising ecological, economic and social aspects of the construction industry. An optimization method that deals with the trade-off among those pillars is needed to approach the overall life span of constructions from a holistic viewpoint. In this study, the insulation thickness of a vapor-open envelope system for subtropical regions with social advantages was investigated by an economic and ecological optimization model, taking into account both initial and running costs under the conditions of 8 cities in Japan. The thermo-hygric minimum thickness was also determined in order to ensure the longevity of the buildings. The following main findings were made: (1) the ecological optimal thickness was larger than the economic optimal thickness, (2) the thermo-hygric minimum was within the economic optimal range in most of the cases, and (3) the interest rate of the currency and the electricity price increase have a significant influence on the result of the optimization analysis. With the aid of the optimization model, it was shown that application of the envelope system is feasible in Japan, especially in the central and southern regions.

Vapor-open envelope




Optimimal insulation thickness

Subtropical climate


Yutaka Goto

Swiss Federal Institute of Technology in Zürich (ETH)

Swiss Federal Laboratories for Materials Science and Technology (Empa)

York Ostermeyer

Chalmers, Civil and Environmental Engineering, Building Technology

Karim Ghazi Whakili

Swiss Federal Laboratories for Materials Science and Technology (Empa)

Holger Wallbaum

Chalmers, Civil and Environmental Engineering, Building Technology

Energy and Buildings

0378-7788 (ISSN)

Vol. 55 December 2012 799-809

Subject Categories

Architectural Engineering

Paper, Pulp and Fiber Technology

Other Materials Engineering

Energy Systems

Building Technologies

Driving Forces

Sustainable development

Areas of Advance

Building Futures (2010-2018)



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4/6/2020 1