Energy-Efficient Moisture Control in Historic Buildings : Linnaeus´ Hammarby as a Case Study

Moisture problems in historic buildings are becoming more frequent, posing risks such as mold growth and material degradation. In culturally significant buildings, climate control must balance energy efficiency with conservation needs. This study investigates energy-efficient moisture control strategies for the east wing of Linnaeus’ Hammarby, aiming to ensure a safe indoor climate without compromising heritage values. Four control strategies were evaluated using hygrothermal simulations in WUFI Plus and WUFI Bio. The control methods were based on either a constant relative humidity (RH) setpoint or Sedlbauer’s mold growth model (LIM curve), where the humidity threshold is adjusted according to the current temperature. The study compared their effects on indoor moisture conditions, system runtime, and energy use. All strategies successfully prevented microbial growth but showed major differences in energy performance. The LIM-based control significantly reduced system operation time and energy demand compared to constant RH control. Additionally, sorption dehumidification proved more energy-efficient than radiator-based systems. The most effective approach combined a LIM I control curve with a sorption dehumidifier, allowing natural climate variation within safe limits. The results underline the importance of adaptive control and appropriate system selection to minimize energy use while ensuring the preservation of historic buildings.