Environmental and energy saving potential from greywater in hotels.

Reducing energy consumption, increasing energy efficiency technologies and solutions, decreasing emissions are very effective tools towards EU environmental policy. The constant demand for domestic hot water (DHW) throughout the year creates great benefits for drain water heat recovery (DWHR) systems in hotels, which is the most promising and significant feature of energy saving potential for the hotel sector in Poland. This paper determines the feasibility of heat recovery in a typical hotel in Poland.

Variability and role of long-wave radiation fluxes in the formation of net radiation and thermal features of grassy and bare soil active surfaces in Wrocław.

The paper examines the variability of long-wave radiation fluxes in two contrasting types of urban active surfaces - grassy surface and surface without plants (bare soil) in Wrocław (Poland) within a 12-year period (August 2007-July 2019). The study used net radiation and heat balance formulas to calculate the share of individual radiation fluxes in these balances, and then utilized the Stefan-Boltzmann formula to calculate the effective temperatures of researched surfaces. The analysis showed the temporal variability of these fluxes against the background of weather and climatic conditions and in relation to the variability of short-wave radiation fluxes.