Measurement data on domestic hot water consumption and related energy use in hotels, nursing homes and apartment buildings in Norway

The data article describes detailed measurements of domestic hot water (DHW) consumption in 12 Norwegian buildings. Included in this study are 4 hotels, 4 nursing homes, and 4 apartment buildings in the greater Oslo region. Flow and temperature measurements were performed on the DHW production system in each building's heating plant, for a duration of at least 6 weeks. The measurements were conducted with an interval of 1 s, and then averaged for 2 s before analysis in order to reduce data noise and measurement uncertainties. The data set includes flow rates, temperatures, energy for consumed hot water (CHW) and distribution losses in the hot water circulation (HWC). Reuse potentials consist of analyses related to flow rates, energy use and distribution losses, e.g. in peak flow rates analysis or DHW energy flexibility simulations. The measurements were performed within the research project “Energy for domestic hot water in the Norwegian low emission Society” (VarmtVann2030).


a b s t r a c t
The data article describes detailed measurements of domestic hot water (DHW) consumption in 12 Norwegian buildings. Included in this study are 4 hotels, 4 nursing homes, and 4 apartment buildings in the greater Oslo region. Flow and temperature measurements were performed on the DHW production system in each building's heating plant, for a duration of at least 6 weeks. The measurements were conducted with an interval of 1 s, and then averaged for 2 s before analysis in order to reduce data noise and measurement uncertainties. The data set includes flow rates, temperatures, energy for consumed hot water (CHW) and distribution losses in the hot water circulation (HWC). Reuse potentials consist of analyses related to flow rates, energy use and distribution losses, e.g. in peak flow rates analysis or DHW energy flexibility simulations. The measurements were performed within the research project "Energy for domestic hot water in the Norwegian low emission Society" (Varmt-Vann2030  Table   Subject Renewable Energy, Sustainability and the Environment Specific subject area Domestic hot water (DHW) consumption and energy use in buildings Type of data CSV files Tables  How data were acquired Flow and temperature measurements were performed on the main supply for 12 buildings.
• Clamp-on ultrasonic flow meters were used for flow measurement (FLUXUS F601 [1] ). • Type-T thermocouples where mounted on the pipe wall (TE Wire & Cable [2] ). • Data logger (Squirrel 2020 [3] ) • Data treatment in python/pandas [4] Data format Raw Parameters for data collection • Measurements on DHW system in 12 buildings: Hotels (4), nursing homes (4), and apartment buildings (4). • Temperatures and flow rates are measured in the heating central, with an interval of 1 s and averaged to 2 s. • Energy for consumed hot water ( Q CH W ) and energy for hot water circulation ( Q HWC ) is calculated.
Description of data collection • At each location, the measurement equipment was installed for a period of minimum 6 weeks. • Measurements with an interval of 1 s are averaged to 2 s, to reduce uncertainty / noise in the measurements. • Data is presented with time steps of 2 s and 1 h.

Value of the Data
• While buildings are becoming more energy efficient, the share of DHW energy is increasing. DHW energy use is often identified as a main source of flexible energy use in buildings, due to the DHW storage tanks. It is becoming increasingly important to understand the energy use and energy losses related to DHW. • The datasets provide temperature and flow rate measurements with high (2 s) resolution in hotels, nursing homes, and apartment buildings. Energy for consumed hot water and energy for hot water circulation is described with high and hourly resolution. Researchers, energy analysts, building owners and industrial players can benefit from the datasets, analysing DHW flow rates, energy use and distribution losses. Detailed data on DHW consumption is important background for development of standards and directives, e.g. related to pipe dimensioning and energy labels. • The datasets can be an important input for various analyses related to flow rates, energy use and distribution losses, e.g. in peak flow rates analysis or DHW energy flexibility simulations. • Data from Norwegian buildings can be useful for studies related to differences in energy consumption between countries and societies.

Description of buildings and measurement periods
Measurements are performed in 12 buildings: 4 hotels (HO), 4 nursing homes (NH), and 4 apartment buildings (AB). The main parameters describing the buildings are shown in Table 1 .
All buildings except NH2 have hot water circulation (HWC) systems, where DHW is permanently circulated in pipes to keep the water hot, compensating for heat losses. However, there were large differences in the layout and several of them do not work as intended. Either they were not properly balanced, so that the water only circulated in a limited part of the system, or blinded after some renovation work on the system. See Table 1 for details. This makes it difficult to compare the losses.
HO1 and HO2 are built according to similar specifications, and are both typical conference hotels, but HO1 does have higher share of non-business guests. HO3 is a more compact city hotel, without restaurant and conference halls. HO4 is also a city hotel, but with a restaurant and large kitchen facilities.
The main difference between the nursing homes is the room density (number of resident rooms per total area). NH3 has a lower room density than the other two buildings. In addition, NH3 has bypassed a large part of the circulation system. In general, most residents in nursing homes have their own room with separate bathroom. Most hot food is made at centralized kitchens and transported to the nursing homes.
For the apartment buildings, most of the apartments in AB1 and AB2 have 1 bedroom, the apartments in AB3 have 2 bedrooms, and the apartments in AB4 have from 2 to 3 bedrooms. AB1 and AB2 are social housing, owned and managed by the state to provide affordable housing for people who need it. AB3 and AB4 are housing cooperatives with privately owned apartments.

Dataset 1: flow, temperature, and energy data with 2 s resolution
Dataset 1 describes flow, temperature, and energy data with 2 s resolution. The dataset is divided in 12 csv-files, one for each building. The csv-files are accessible from [7] , labeled [building ID]_1. Table 2 shows the parameters available for each of the buildings. Some general comments to the data: • Data timestamps are given in Central European Time (CET), which is GMT + 1. Daylight saving time (DST) applies. • The data is unfiltered (except for the 2 s average) and especially the flow measurements therefore have significant noise. • In some buildings systems had malfunctioning non-return valves, resulting in periods with negative flow rates and increased cold-water temperatures.

Dataset 2: energy data with hourly resolution
Dataset 2 describes energy data with hourly resolution. The dataset is divided in 12 csv-files, one for each building. The csv-files are accessible from [7] , labeled [building ID]_2. Table 3 shows the parameters available for each of the buildings.

Measurement equipment
Detailed measurements of water flow and temperature were performed on the DHW production system in each building, for a duration of approx. 6 weeks. The measurements were conducted with an interval of 1 s, and then averaged for 2 s to reduce measurement uncertainties and noise. In order to avoid modifications to the water installations, non-intrusive clamp-on ultrasonic flow meters and Type-T thermocouples mounted on the pipe outer wall were used. The flow meters have a specified accuracy of 1.6% of reading ±0.01 m/s [1] , and the Type-T thermocouples have an error specified as maximum of 1.0 °C or 0.75% above 0 °C [2] . For the flow meters, pipe diameter and thickness are needed as input. For copper piping thickness was measured with an accompanying tool, while for alupex piping, manufacturer data was applied. Thermocouples were mounted on the outer pipe wall and fixed with aluminium tape, and then insulation was added on the outside. All data was logged with a local logger [3] , to avoid issuse with wireless data transfer and connection.

Measurement setup
There are variations in how DHW systems in Norway are designed, both in regard to energy sources, but also with respect to system layout. Fig. 1 shows a principle drawing of how most heating plants are built, with typical measuring points used in the DHW measurements. When  Measurements performed for each of the buildings, in addition to the data presented in Table 2 .  Table 2 are available with the article. The values are either measured ( Table 2: T_cw, T_hw, T_hwc, V_hwc, V_chw; Table 4: T_hwt, V_cw, V_cwt, V_hw) or calculated ( Table 2: V_chw, P_chw, P_hwc). The calculations are presented in the next section.

Water for hot water production
Consumed DHW flow rate ( ˙ V CHW ) is the same as cold water flow rate into the production unit ( ˙ V CW ). Some buildings had short pipe sections where the flow branches off. This made it challenging to achieve accurate measurements of ˙ V CW without interference from adjacent pipe runs. For these buildings, ˙ V CW was calculated according to Eq. (1) .

Power and energy flows
Power for consumed hot water ( ˙ P CHW ) and heat loss ( ˙ P HWC ) are calculated according to Eqs. (2) and (3) , respectively. h(T) denotes the specific enthalpy of water at temperature T, and ρ is the density of the water at the temperature of which the flow rate is measured. The hourly energy flows (Q) are calculated as the mean of the power within each hour.

Ethics Statement
Data are provided with consent from the building owners.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article.