.Buildings.ThermalZones.ISO13790.Zone5R1C.Zone

Thermal zone based on 5R1C network

Information

This is a lumped-capacity simplified building model based on the 5R1C network presented in the ISO 13790:2008 Standard. The simplified 5R1C model uses five thermal resistances and one thermal capacity to reproduce the transient thermal behaviour of buildings. The thermal zone is modeled with three temperature nodes, the indoor air temperature TAir, the envelope internal surface temperature TSur and the zone's mass temperature TMas (the heat port is not shown in the figure), and two boundary condition nodes, supply air temperature TSup and the external air temperature TExt. The five resistances are related to heat transfer by ventilation HVen, windows HWin, opaque components (split between HTra and HMas) and heat transfer between the internal surfaces of walls and the air temperature HThe. The thermal capacity Cm includes the thermal capacity of the entire zone. The heating and/or cooling demand is found by calculating the heating and/or cooling power ΦHC that needs to be supplied to, or extracted from, the internal air node to maintain a certain set-point. Internal, Φint , and solar, Φsol, heat gains are input values, which are split in three components.

The ventilation heat transfer coefficient H_ven is calculated using

H_ven = ρ_a c_a ∑_kV̇_k,

where ρ_a is the density of air, c_a is the specific heat capacity of air and V̇_k is the k-th volumetric external air flow rate. The coupling conductance H_the is given by

H_the = h_as A_tot,

where h_as is the heat transfer coefficient between the air node the surface node, with a fixed value of 3.45 W/m²K, and A_tot is the area of all surfaces facing the building zone. The thermal transmission coefficient of windows H_win is calculated using

H_win = ∑_kU_win,kA_win,k,

where U_win,k is the thermal transmittance of window element k of the building envelope and A_k is the area of the window element k of the building envelope. The coupling conductance H_mas is given by

H_mas =h_ms f_ms A_f,

where h_ms is the heat transfer coefficient between the mass node and the surface node, with fixed value of 9.1 W/m²K, f_ms is a correction factor, and A_f is the floor area. The correction factor f_ms can be assumed as 2.5 for light and medium building constructions, and 3 for heavy constructions. The coupling conductance H_tra is calculated using

H_tra = 1 ⁄ (1 ⁄ H_op - 1 ⁄ H_mas),

where H_op is the thermal transmission coefficient of opaque elements. The three heat gains components are calculated using

Φ_air = 0.5 Φ_int,

Φ_sur = (1-f_ms A_f ⁄ A_tot -H_win ⁄ h_ms A_tot)(0.5 Φ_int+ Φ_sol),

Φ_mas = f_ms A_f ⁄ A_tot (0.5Φ_int + Φ_sol).

Tips for parametrization

The parameters AWin, AWal, surTil and surAzi must have the same dimension of nOrientations .
The areas in AWal must account only for the opaque parts of the walls (excluding windows). The floor and roof area is entered through AFlo and ARoo and must not be entered as part of AWal.
If a wall contains only opaque parts, the corresponding window area must be set to 0.
The parameter coeFac is used to vary the g-factor as a function of the incident angle of the surface. Often, the curve can be approximated by a cubic polynomial, as shown in Buildings.ThermalZones.ISO13790.Validation.BESTEST.Case600. When this information is not available, the parameter coeFac must be set to 1.

Revisions

May 8, 2024, by Michael Wetter:
Removed connection to itself.
Mar 16, 2022, by Alessandro Maccarini:
First implementation.

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