Energy efficiency in mass timber buildings: Novel methodologies expose significant advantages.
For nearly a century, thermal energy demand calculations have been based on simplified models, according to the technical potentials of the particular period. 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, conductivity coefficients of building materials and heat transfer coefficients where initially agreed on. In 1959, when the third edition was adapted, heat transfer coefficients and modern building materials were included. Ever since, at least for mass timber buildings, the coefficients for conductivity have been subject only to incremental and rather insignificant innovative change. Hot box assessment methods, basically designed for light thermal insulation, have been used to assess mass timber buildings ever since, generally ignoring thermodynamic characteristics, which have demonstrated major advantages in mass timbers buildings in praxis. Novel methodologies have been applied in the research performed at Oak Ridge National Labs, Tn. The inclusion of the thermal comfort approach according to DIN 7730 and/or ASHRAE Standard 55; as well as the differentiation between thermal infrared radiation and convective heating, have demonstrated significant differences in the energy requirement assessments performed dynamically. The results of the research bring the assessment data much closer to the anticipated heating demand in praxis. Thermal inertia, inner surface temperatures, thermal emissivity, solar gains, dynamic outer weather conditions and thermal comfort characteristics are finally combined into a holistic assessment approach regarding thermodynamic relationships. These results can potentially be applied towards the contribution of energy efficient mass timber builds; and, moreover, to material efficient mass timber buildings at the same time, whilst material efficiency is becoming ever more important.