A control method for increasing the heat usage efficiency of nearly-zero-energy buildings with heat pumps

H. Pihlap¹*, A. Annuk¹, M. Lehtonen², S. Muiste¹, A. Tooming¹ and A. Allik¹

¹Estonian University of Life Sciences, Institute of Technology, Chair of Energy Application Engineering, Kreutzwaldi 56, EE51006 Tartu, Estonia
²Aalto University, Department of Electrical Engineering and Automation, Maarintie 8, Espoo, Finland
*Correspondence: heino.pihlap@emu.ee

Abstract:

In the retrofitting of older buildings with central heating into nearly zero-energy buildings more and more air to water heat pumps are used. These heat pumps are normally connected to heating systems, producing heat only on demand. The greatest demand for heat occurs when the outside temperature and therefore the COP of the pump is lowest. Outside temperature varies during the day, meaning it is possible to save energy by producing and storing heat in a situation where the COP is higher. To determine the periods with higher COP values weather forecast data and COP curves are used. The data enables to rank and select time periods for heat production. This in conjunction with the heat demand curve of the building enables to create an operation schedule for the heat pump. The aim of the study is to develop heat pump control methods for renovated buildings to comply with nearly zero energy building codes. Dependent on the heat pump and weather conditions, up to 10 % of the electricity demand for heating can be decreased.

Key words:

heat demand modelling, heat production scheduling, heating season, optimization, temperature fluctuations

Measurement and analysis of temperature changes of ground massif with Slinky heat exchanger

M. Šeďová*, P. Neuberger and R. Adamovský

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ16521 Prague – Suchdol, Czech Republic; *Correspondence: sedova@tf.czu.cz

Abstract:

The article is describing temperature changes in the ground massif with Slinky heat exchanger. The exchanger serves as a heat source for a heat pump which is used for cold water warming and a heating of the administration building. The aim of the research is to analyse the influence of the Slinky heat exchanger to the temperature of the ground massif while extracting heat energy at the beginning and during the heating season, as well as beyond it. The temperature process of the ground massif is described near the exchanger, on a reference lot in burial depth of the heat exchanger and also in a depth of 0.2 m. The energy potential of the ground massif was evaluated using the temperature differences of ground massif in the area of the Slinky heat exchanger at the beginning and at the end of the heating season.

Key words: