There is an increased trend of global awareness and discussions on the contribution of building designs and materials in global warming and greenhouses gases emissions. The use of wood materials in the construction sector is also increasing hence linked to forest industries and conservation, building sector, global warming and global climate change. The construction sector contributes directly and indirectly to environmental degradation and greenhouses gases emissions. With the current global awareness on climate change and adaptation, the substitution of wood products in the construction sector in Tanzania is inevitable. Despite its signiicant growth, the substitution of sawnwood by different alternatives in Tanzania is not well examined. Therefore, this study forecasted the substitution of sawnwood for year 2016, 2021 and 2026 for Dar es Salaam using income elasticity of demand to explain the effects of these substitutions to the environment. The consumption of sawnwood in none storey buildings, medium category and high category buildings were 2.69 m 3 , 3.1 m 3 and 5.3 m 3 respectively. In 2012, Dar es Salaam consumed a total of 8,706.9 m 3 of sawnwood for doors and window frames in about 2878 new buildings. Kinondoni district consumed 42.2%, Ilala district 34.8% and Temeke district 23% of the total sawnwood. The per capita sawnwood consumption for building in Dar es Salaam in 2012 was 2.7 m 3 while for aluminium was 46.2 m 2 . Windows showed high substitution of sawnwood compared to doors with aluminium being the main substitute material. The forecasted per capita consumption of sawnwood and aluminium materials for buildings in 2026 was 3.4 m 3 and 86.8 m 2 respectively. Sawnwood consumption in none storey buildings is increasing as a results of high rate of urbanization and economic growth hence increased number of middle-income population which causes an increased demand and construction of houses for residential purposes. The increased demand for construction materials have negative impacts to the environment where these materials are harvested. We recommend further research on the effects of substitution of sawnwood and the promotion of lesser-known and underutilized sawnwood species to strengthen wood industry in Tanzania due to the current high demand of sawnwood and high substitution rates.