Timber framed walls that contain high thermal masses can help lower energy consumption; however, many individuals are unfamiliar with what constitutes “high thermal mass”.
Materials with high thermal mass absorb solar heat during the day and then release it through night-time radiation, thus moderating internal temperatures and decreasing air conditioning costs. This technology reduces air conditioning requirements substantially.
Thermodynamics
Timber’s sustainability, strength, and biophilic properties are well-known to builders; however, its thermal benefits often go overlooked. By including heavy timber into a building’s design, its thermal mass helps regulate indoor temperatures while simultaneously decreasing energy consumption while improving year-round comfort levels. Thermal mass refers to any material’s ability to absorb, store, and gradually release heat energy over time.
High-thermal mass materials like brick walls and tile floors absorb energy from sunlight as well as internal sources such as people and equipment, before slowly releasing it again during evening and night time to regulate home temperatures and help to balance seasonal changes in outdoor air temperatures. This process is known as thermal lag.
Timber boasts an exceptional volumetric heat capacity, enabling it to absorb large amounts of thermal energy before slowly dissipating it when temperatures shift. Furthermore, its hygroscopic nature helps regulate indoor humidity levels and minimize mold risks.
Timber can serve as an efficient thermal battery in any home, with dense species like oak and Douglas fir acting like sponges to absorb and store heat until ambient temps drop; then release it later, saving energy consumption and emissions.
To maximize its benefits, thermal mass must be used alongside appropriate insulation to avoid unwanted heat loss through drafts and air leaks. Proper insulation also ensures that heat absorbed by thermal mass does not escape through drafts and air leaks.
As you determine the thickness of timber for your next project, it’s essential to remember that nominal and actual sizes may differ due to how it’s processed. Nominal sizes typically refer to dimensions as they come out of a mill; while actual sizes take into account shrinkage that occurs as wood dries as well as sawing techniques (plainsawn, riftsawn or quartersawn). Furthermore, regional standards can influence nominal and actual sizes; choosing an optimal timber size can have an enormous effect on efficiency and aesthetic. Choosing an optimal timber size could make or break an entire project’s efficiency or aesthetic value! Choosing an effective timber size can have major ramifications on efficiency as well as aesthetic benefits in any project! Choosing the appropriate timber size can have significant impacts both efficiency and aesthetic qualities in any endeavor – making use of suitable timber sizes can transform efficiency and aesthetic of projects significantly while simultaneously.
Thermal Conductivity
Timber’s ability to absorb and store heat energy is one of the major assets it brings to buildings, helping to moderate temperature variations while acting as a thermal battery. Furthermore, wood has a hygroscopic nature which helps manage humidity levels indoors while mitigating mold risks.
Thermal properties of solid wood vary based on both its density and moisture content, which makes evaluating them in-situ testing problematic and time-consuming. Therefore, typical lab methods used to measure them entail using small samples that must be kept in constant temperature contact with metal plates, making in-situ testing impractical; furthermore these processes limit the number of specimens which can be investigated in one study.
As such, it is imperative that more efficient methods for measuring thermal conductivity of timber-based materials be developed. One potential approach would be examining correlations between relative dielectric constant and thermal conductivity: dielectric constant is directly tied to moisture content levels in materials so this correlation could allow users to predict conductivity of materials without first needing to establish their type.
As shown in Fig. 6a, an R2 score of 0.87 indicates a strong relationship between paulownia’s measured relative dielectric constant and thermal conductivity properties, and their respective thermal conductivities. Furthermore, most measurement uncertainties fall within 10% of the regression line’s regression line-indicating most readings within 10% uncertainty-with larger values denoting higher moisture content levels while smaller values represent dryer samples.
While this correlation is encouraging, it should also be remembered that its effect may also be affected by other factors like grain direction and wood anatomy. Therefore, further research needs to be done in order to develop an instrument capable of automatically determining a material’s dielectric constant from its thermal conductivity.
As part of a larger study analyzing heat and mass transfer between hybrid cross-laminated timber (CLT) panels consisting of LSL and red spruce laminae, we recently investigated the relationship between through-thickness thermal conductivity of these materials and moisture content, using this research to create a predictive model for through-thickness thermal conductivity between LSL and red spruce laminae with various moisture contents.
Density
Wood density or specific weight is an essential consideration when selecting construction timber. This ratio measures the volumetric density of wood relative to water (excluding air). As an example, one cubic metre of Eucalyptus has a density of 1 kg/m3.
Comparatively, concrete has a density of 3 kg/m3.
Timber thickness and its relationship with density is essential to understanding its mechanical properties. When subjected to bending, shear, compression or tension tests, lower density means weaker timber while higher densities result in greater stiffness – this property makes floors and rafters resistant to excessive deflection from working loads without feeling unsteady and creating the appearance of sagging timbers.
Although differences among commercial timber species are evident, individual pieces’ average densities depend on factors like how fast a tree was growing when felled and its moisture content. Sawing techniques and regional regulations also play a part in shaping these characteristics.
Density and DBH have an intriguing correlation, suggesting that sawmill production is negatively correlated with stand density while positively related to basal area and total timber volume. This may be explained by higher density trees producing equal amounts of sawmill and energy wood from given height and basal area conditions.
Wood is an effective insulator due to its cellular structure which allows it to store heat by absorbing air into its pores, acting like an energy storehouse while slowly releasing it as temperatures decrease. This effect is further magnified with dense timbers such as oak and Douglas fir where their dense cellulose fibers create an effective thermal transfer barrier, keeping heat inside their structures and keeping people comfortable throughout winter. Timber buildings offer the ultimate winter living comfort due to these properties of wooden insulation.
Moisture Content
Moisture is a naturally occurring substance found throughout nearly all materials, pervading its molecular structures and having an enormous influence on their physical characteristics; weight, thermal expansion, amalgamation and electrical conductivity can all be altered by even minimal amounts of moisture.
Food production requires accurate moisture control, and improper levels can have devastating effects. Excessive or deficient moisture levels can have adverse impacts on all aspects of a food’s physical characteristics – from appearance and flavor, through taste and texture – as well as machinery used in production by creating condensation build-up that requires expensive repairs downtimes.
Producers rely heavily on accurate methods of moisture content measurement to monitor production quality, whether through spectroscopic, chemical, electrical conductivity and thermogravimetric methods or instruments. For best results it is crucial that samples selected for testing accurately represent the entire batch being tested – to achieve this, randomly drawn and collected from throughout the batch should be used instead of selecting single areas to collect samples from.
Also essential is having a test instrument capable of simultaneously measuring both moisture content and water activity. A good moisture meter should have the capability of doing both by loading up isotherm models specific to the material being tested, eliminating complex calculations by the user.
An expedient test result is essential in order to apply it at the point of production and make adjustments before product quality deteriorates, guaranteeing maximum productivity while preventing costly production pauses or product losses that would reduce downtime costs and enhance productivity.
Decagon has addressed this challenge with their AquaLab Series 4TE Duo moisture analysis instrument, which uses a chilled mirror to measure water activity of products before converting that data to their moisture content via isotherm models. As it’s the only moisture analysis instrument on the market that offers both measurements, saving both time and effort by eliminating cumbersome calculations processes.
