Extensive building usage schedules for energy simulation completed with detailed consumption of domestic hot water

Abstract

The main purpose of this study was to develop building usage profiles for usages such as domestic hot water (DHW), occupancy, lighting, and appliances to support the knowledge-based energy estimation for low and nearly zero energy buildings.

Our study developed the monthly and hourly DHW usage profiles for Finnish apartment buildings based on onsite measured data. The average daily DHW usage was 43 L/(person. day) whereas the minimum and maximum were reported during July (37 L/(person. day)) and November (47 L/(person. day)), respectively. The daily usage mostly varied between 20-70 L/(person. day). Moreover, a specific selection procedure was used to develop the DHW hourly usage profiles for multiple occupant groups. These profiles had two sharp usage peaks in the morning and evening. DHW usage was 2-4 times higher during peak hours compared to non-peak hours. Also, usage peak at morning shifted 2-3 hours later during weekends (WE), whereas evening usage remained in the same period as on weekdays (WD). In addition, smaller occupant groups had higher DHW usages during peak hours than the larger groups. Furthermore, a bottom-up model was formulated to quantify the correlation of DHW usage patterns, which could predict the hourly usage of DHW for any unknown datasets. The developed equations can be used directly in simulation tools for estimating the DHW volume and corresponding energy use.

The development of hourly schedules of occupancy, appliances, and lighting for ten building categories are also reported separately for WD and WE, based on the synthesis of existing literature. This approach makes it possible to consider the static behaviors of occupancy, lighting, and appliances, which require limited input data. Heat emission modelling from occupant bodies in 10 building categories has shown the contribution of heat and humidity from the occupants.

Finally, the developed profiles were used in a simulation tool with the intention of sizing the monovalent ground source heat pump (GSHP) power for a Finnish single-family house. An alternate control system for space and DHW heating was developed in a plant model, making it possible to provide 100% of heat for space and DHW heating. In addition, heating power equations were developed which are suitable for computing any type of heat pump sizing power that follows the same alternate operation principle and hydronic heating facilities. The developed equations predicted the heating power of GSHP with variations of 0-2.2% compared to the simulated results. Moreover, DHW heating accounted for 13-26% and 21-41% of total heating power at design outdoor temperatures of -26 °C and -15 °C, respectively. In contrast, internal heat gains from occupancy, lighting, and appliances reduced the total heating power by 3-19%. The results showed that internal heat gains reduced the GSHP power by 0.62 kW, which was equivalent to the contribution of DHW heating power (0.63 kW) for a single-family house with three occupants.