Optimal setpoint operation to reduce peak drying of a church organ

Abstract

The paper presents the characteristics of the Walloon Church in Delft (Netherlands) and a description of constraints for the indoor climate, giving criteria for the indoor air temperature and relative humidity with the focus on the preservation of the monumental church organ. The set point operation of the Heating Venting and Air Conditioning (HVAC) system is evaluated by simulation. The next main model components are presented and combined in a single integrated model: 1) a whole building response model for simulating the indoor temperature and relative humidity, 2) a Partial Differential Equation (PDE) based model for simulating detailed dynamic moisture transport in the monumental wood (church organ) and 3) a SimuLink controller model. The building model is validated with measurements. The main advantage of the integrated model is that it directly simulates the impact of HVAC control set point strategies on the indoor climate and the church organ. Two types of control strategies are discussed. The first type is a limited indoor air temperature-changing rate. The second type is a limited indoor air relative humidity changing rate. Recommendations from international literature suggest that 1) a changing rate of 2 K/h will preserve the interior of churches and 2) a limited drying rate is important for the conservation of monumental wood. This preliminary study shows that a limitation of indoor air temperature changing rate of 2 K/h can reduce the peak drying rates by a factor 20 and a limitation of the relative humidity changing rate of 2%/h can reduce the peak drying rates by a factor 50. The second strategy has the disadvantage that the heating time is not constant.