Dataset from the zero-energy log house project

In this data article, we present a supplementary dataset from a zero-energy log house project in southern Finland, presented in detail in [1]. This article consists of comprehensive energy-related data collected in practice from several sources from the house during the period of 2017−2019. The data include solar PV production data of two separate systems, in south and east−west directions. The solar PV data are presented on a different time scale to demonstrate the operation of two installations in different seasonal conditions. Simulated results are also included. The electrical energy consumption is distributed between the consumer, ventilation, the ground source heat pump for space heating and the domestic hot water energy at the monthly level. The realized electrical energy prices, self-sufficiency rates, and costs are also presented at the monthly level. The heat production of the ground source heat pump is estimated according to the service hour data and the performance data given by the manufacturer. The data can be applied in new and building-under-renovation projects.


Specifications
Renewable Energy, Sustainability and the Environment Specific subject area Building engineering, Zero-energy building, Energy efficiency Type of data

Value of the Data
• Measured three-year operational energy data in a single-family log house in southern Finland that is a plus energy building. Energy data consist of south and east-west facing solar PV system productions in the same site, a ground source heat pump (GSHP) as a main heat source, other electricity consumption (ventilation and consumer), self-sufficiency rates of the solar PV electricity without a stationary battery when the GSHP-based heating is controlled. • The data can be valuable and useful for researchers, engineers, architects, manufacturers, designers, energy policy makers, and end-users. In addition, data work as an eye-opener for them who are involved in the future plus energy buildings. • The measured practical dataset can be used as a reference material to verify models, load and production forecasting, and practical data in other similar buildings. In addition, it works as an education material.

Data Description
A shadowless location guarantees high performance of the solar PV plant production at an annual level to reach the local production potential estimation, which is about 10 0 0 kWh E /m 2 in southern Finland [2] . The position of the sun varies considerably in Nordic locations depending on the season, from a low position in wintertime with a short day length to a high position in summertime with a long day length. The production curves for each panel string (east 5.355 kWp, west 5.355 kWp, south1 5.20 0 kWp, south2 5.20 0 kWp) on a clear summer day are presented in Fig. 1 (a). The inverter-specific production curves (south 10.4 kWp, east-west 10.71 kWp) for the same day are presented in Fig. 1 (b). All the raw data for the figures are reported in the Supplementary Material. The monthly level productions both for the south and east-west installations during a three-year period including local simulated production are presented in Fig. 2 .  The performance of the solar PV production is generally described with annual production related to the installed capacity, generally called specific yield. The specific yields of solar PV electricity for the south and east-west installations are gathered in Table 1 . The seasonal performance of the solar PV installations with unequal orientations can be seen in the daily graphs. Figs. 3-5 show the daily solar PV production rates of the south and east-west installations for each month during a three-year period.

Table 2
Electricity self-sufficiency rates of the consumption at the monthly level during the period of 2017 −2019.

Self-sufficiency rate (%)
Year The distribution of electricity consumption at the monthly level in the zero-energy log house for a three-year period is illustrated in Fig. 6 . The solar PV electricity self-sufficiency rates of the consumption according to [3] at the monthly level are depicted in Table 2 . According to [4] , the purchased electricity price is approximately three times as high as the price of the sold electrical energy. The realized purchased and sold electricity prices without basic fee at the monthly level during a three-year period are gathered in Table 3 . The realized electricity total cost for the purchased electricity with a monthly basic fee and the sold and self-consumption electrical energy at the monthly level during a three-year period are gathered in Table 4 .

Experimental Design, Materials and Methods
The solar PV production simulations were driven by the HOMER software, which uses weather and irradiation data gathered by NASA [5] . The solar PV production data with 5 min resolution were collected monthly from the interface of the SMA Sunny Tripower inverters (70 0 0TL for the east-west system and 90 0 0TL for the south system, see  Explorer software. In addition, DC and AC power data were collected from the inverters with the Rasperry PI-based software through the SunSpec® Modbus® interface in a 5 s time frame. The solar PV system installations are presented in Fig. 8 . The purchased and sold electrical energy values were collected through an online web system of the local electricity distribution company at an hourly resolution. The automatic meter reading device was Aidon 6460SE MeshNET, which measures power instantly from each three phases separately and records the measured electrical energy to two registers (purchase and sale). Both the purchase and sale can occur at the same time, if there is an imbalance between production and consumption. In addition, electrical power/energy data were collected from a Siemens SENTRON PAC3200 power monitoring device with the Rasperry PI-based software through the Modbus® TCP interface in a 5 s time frame. The power monitoring and Rasperry PI hardware installations are presented in Fig. 9 . Hourly electrical energy prices were collected from the historical market data service of Nord Pool [6] .
The service hour values of the Nibe F1145-6 ground source heat pump were collected through the NIBE Uplink TM online web system. The measured input power of the heat pump was about 1.5 kW. Based on the manufacturers' information, the COP values used for the space and DHW heating were 4.5 and 2.5, respectively. The measured input power of the ventilation machine was about 80 W.
Data were handled and plotted mainly by the Excel software, but also MATLAB was used. Electrical energy self-consumption was calculated as follows where E E , solarPV is the electrical energy produced by the solar PV systems, and E E , sold is the electrical energy sold to the grid. The consumption was calculated as follows: where E E , purchased is the electrical energy purchased from the grid.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.