Impact of Mass Wood Walls on Building Energy Use, Peak Demand, and Thermal Comfort

For nearly a century, thermal energy demand calculations have been based on simplified models limited by the technical potentials of the period. The first action took place in Germany and Austria in 1929, when the initial technical standards committee for heating was founded. The calculation methods initiated then, to a surprisingly significant extent, still apply today. In addition to the climate zones for German and Austrian locations, initial consensus established conductivity coefficients of building materials and heat transfer coefficients. In 1959, heat transfer coefficients and modern building materials were integrated. Ever since, at least for mass timber buildings, the coefficients for conductivity have been subject only to relatively insignificant innovative change. Steady-state hot-box assessment methods have been used to assess mass timber buildings, generally ignoring thermodynamic characteristics, which have demonstrated significant advantages in mass timber buildings in practice. Novel methodologies have been applied in the research performed at a US DOE national laboratory. The inclusion of the thermal comfort approach based on and in accordance with DIN 7730 and ASHRAE Standard 55 has demonstrated significant differences in the energy requirement assessments performed dynamically. The research results bring the assessment data much closer to the anticipated heating demand in practice. Thermal inertia, inner surface temperatures, thermal emissivity, solar gains, dynamic outer weather conditions, and thermal comfort characteristics are finally combined into a holistic assessment. These results can potentially be applied towards the contribution of energy-efficient mass timber buildings; and, moreover, to material-efficient mass timber buildings at the same time, while material efficiency is becoming ever more important.