UBC Theses and Dissertations
Modelling the decay patterns and harvested wood product pools of residential houses Xie, Sheng H.
The harvested wood products (HWP) in use carbon pool plays a beneficial but frequently unrecognized role in climate change mitigation by storing carbon that has been removed from the atmosphere and providing services that can substitute for emission intensive products. Countries with a culture of building houses with wood use a majority of HWP for structural purposes and, due to the long-lived nature of houses, the structural HWP within these dwellings can last for a long time. Long-lived products have the potential to make a major contribution to the HWP in use pool and accurate quantification of this pool is an important topic worthy of detailed investigation. This study reviewed published HWP decay models and developed a “regression-aggregation-fit” methodology to accurately model the inverse sigmoidal decay patterns of houses at the national level. Using this method, the end-use half-lives of U.S. single-family and multi-family houses, U.S. mobile homes, Canadian residential houses and Norwegian residential houses were estimated to be 137 years, 44 years, 92 years and 146 years, respectively. For comparison, the default product half-lives recommended by the IPCC are 35 years for sawnwood and 25 years for wood-based panels. The direct application of these default product half-lives to quantify the HWP pool in houses is likely to result in substantial underestimation of this carbon pool. The Gamma distribution model was shown to be the most applicable generalized model for describing the country-specific decay pattern of houses. It adequately modelled housing data sets from three different countries and it was the best of the six models evaluated. This model was used to quantify the structural HWP pool in U.S. single-family and multi-family houses and in 2009 this pool was 668 Tg C, which was about 20% larger than published estimates. A constant mass input scenario indicated that this pool may act as a sink for about 750 years with a saturation value of about 1.2 Pg C. This methods developed in this thesis should improve the accuracy of national greenhouse gas inventory reporting for countries with extensive forests and a tradition of building with wood.
Item Citations and Data
Attribution-NonCommercial-NoDerivs 2.5 Canada