**Determination of the Energy Performance of a Solar Low Energy House with Regard to Aspects of Energy E** ffi**ciency and Smartness of the House**

## **Dorota Chwieduk \* and Michał Chwieduk**

Institute of Heat Engineering, Faculty of Power and Aeronautical Engineering, Warsaw University of Technology, 00665 Warsaw, Poland; michal.chwieduk@itc.pw.edu.pl **\*** Correspondence: dorota.chwieduk@itc.pw.edu.pl

Received: 15 May 2020; Accepted: 17 June 2020; Published: 22 June 2020

**Abstract:** The paper shows how di fficult it is to prove technically that a building really is both low energy and smart, and that all aspects of energy e fficiency have been treated equally. Regulations connected to the determination of the energy performance of residential buildings take into account only space and hot water heating energy consumption and define the indices of maximal primary energy consumption, but not energy needs based on the architecture of the building. A single family house designed and constructed as a low energy solar house in Warsaw's suburbs is considered. Availability of solar energy and its influence on the architecture of the house is analyzed. A specific solar passive architectural concept with solar southern and cold northern bu ffer spaces incorporated into the interior of the house is presented. Parameters of the building's structure, construction materials, as well as operation parameters of equipment and heating systems based on active use of solar energy, ground energy (via a heat pump) and waste heat from a ventilation system are described. Results of calculations give values of final and primary energy consumption index levels of 11.58 kWh/m<sup>2</sup> and 25.77 kWh/m2, respectively. However, the o fficial methodology for determination of energy performance does not allow for presenting how energy e fficient and smart the building really is.

**Keywords:** energy performance of buildings; solar passive systems; low energy buildings; energy e fficiency; smart buildings
