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In thermally modernised buildings, sharing of ventilation heat loss becomes more significant. In the case of the application of ventilation with heat recovery, especially during transitional periods, there arises a question of whether an air system makes it possible to maintain the required indoor air temperature without the necessity of using a basic hydronic heating system. This paper presents the application of a simple thermal network model of a building zone to simulate indoor air temperature in a single room of a multi-storey building with a mechanical ventilation system with heat recovery. Ventilation air was supposed to be the only heat source and its ability to maintain the required indoor air temperature was checked in simulations and then compared with measurements. The 5R1C thermal network model of a building zone was used for simulations. Comparison with measurements showed the Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) of indoor air calculation to be 2.37 °C and 2.45 °C, respectively. When including heat flux from the bottom storey through the floor, MAE = 1.28 °C and RMSE = 1.38 °C were obtained. [ABSTRACT FROM AUTHOR]

Costs of cooling installations cause them to be very rarely used in residential buildings in countries located in heating-dominated climates, like Poland. Hence, there arises the need to assess indoor thermal comfort during summer and to indicate ways to reduce possible overheating. This paper presents an attempt to use the thermal network model of the building zone of EN ISO 13790 to assess indoor operative temperature during four warm months from June to September. The model of the naturally ventilated single-family residential building located in central Poland was used. Performed calculations for the base case resulted in 38 and 63 days within the comfort zone at 80% acceptance level in a total of 122 days in the analyzed period for EN 15251 and ASHRAE standards, respectively. Use of external shading on windows and the roof with lower solar absorptance resulted in 46 and 70 days with acceptable conditions, respectively. Further application of night ventilation resulted in the 38 and 63 days, respectively. From the considered solutions in Polish climate conditions, windows shading seems to be the most efficient solution when controlling indoor comfort in residential buildings with no cooling system. A comparison of hourly operative temperature from that model with the detailed simulation in EnergyPlus showed a strong correlation with R2 = 0.934. [ABSTRACT FROM AUTHOR]

The hourly dynamic calculation method given in EN ISO 13790 uses a lumped-capacity 5R1C thermal network model of a building. This model enables the use of hourly occupancy patterns. But introduction of hourly ventilation schedules is not recommended because in some equations of the calculation procedure division by zero appears when the infiltration and ventilation airflows are zero. This paper presents a modified 4R1C version of the 5R1C model. The existing ventilation heat transfer was replaced by the new heat flux modelling the time varying airflow due to infiltration and ventilation. The calculation method to obtain heating and cooling power required to maintain internal set point temperatures was presented in details. The new model was validated against EN 15265 with the error up to 6.7% and 5.4% for heating and cooling, respectively. Only in the test 10 for heating the error was 31.6%. BESTEST tests were passed successfully, except for the minimum annual temperature of −19.3°C which didn't fall within the reference range in the test 600FF. In simulations of the single family building the coefficient of determination of the calculated internal operative temperature and thermal power against reference EnergyPlus results was R2 > 0.844 and R2 > 0.811, respectively. [ABSTRACT FROM AUTHOR]