Miljølaster

Miljølaster is a term used especially in Danish engineering to describe the environmental loads that act on structures, components, and products due to surrounding conditions. It refers to external, time-variant forces generated by the environment, distinct from permanent dead loads or usage-based live loads. Miljølaster can influence the durability, performance and service life of objects, and are considered alongside mechanical and operational loads in design and assessment.

The concept covers several categories. Thermal loads arise from changes in temperature and temperature gradients, leading to expansion, contraction and potential material fatigue. Moisture-related loads come from humidity, rain, condensation and freeze–thaw cycles, which can drive swelling, cracking or corrosion. Solar radiation and UV exposure cause aging and material degradation. Weather-related loads include wind, snow, ice and rain, which impose additional dynamic or static forces. Chemical environmental loads involve exposure to chlorides, pollutants, acids and other aggressive substances that can accelerate corrosion or degradation. In some contexts, biological growth and surface contamination, as well as soil and groundwater conditions, may act as environmental factors affecting performance.

In practice, miljølaster are incorporated into design codes and durability analyses. Designers use climate data, exposure classes and reference years to derive design values for environmental actions, and regulatory standards guide testing and verification through environmental cycling and aging simulations. The concept supports ensuring safety, reliability and long-term performance in Nordic and international engineering projects.