.IDEAS.BoundaryConditions.SimInfoManager

Information

The SimInfoManager manages all simulation information. It loads TMY3 weather data files and applies transformations for computing the solar irradiance on the zone surfaces.

Typical use and important parameters

• Parameters filNam and filDir can be used to set the path to the TMY3 weather file. This file should include the latitude, longitude and time zone corresponding to the weather file. See the included weather files for the correct format.

Options

• IDEAS contains an efficient implementation for computing the solar incidence angles on surfaces that are part of large building models. When a model has many parallel surfaces the default implementation computes the solar irradiance separately for each of these surfaces, while the result for all of them should be the same. The SimInfoManager computes five default orientations (azimuth angels): south, west, east, north and horizontal. Whenever a surface needs the solar incidence angels for one of these orientations these precomputed values will be used. The default orientations can be changed using parameters incAndAziInBus. incAndAziInBus determines for which inclination and azimuth the solar radiation is pre-computed.
• Conservation of energy within the building can be checked by setting computeConservationOfEnergy=true. Conservation of energy is checked by computing the internal energy for all components that are within "the system" and by adding to this the integral of all heat flows entering/leaving the system. There are two options for choosing the extent of the system based on parameter openSystemConservationOfEnergy. Either conservation of energy for a closed system is computed, or it is computed for an open system.
  When choosing the closed system the conservation of energy check should always work when using IDEAS as intended. In this case conservation of energy is only checked for all components in the Buildings package. I.e. all heat flows at embedded ports port_emb of walls, fluid ports of the zones, zone.gainCon and zone.gainRad are considered to be a heat gain to the system and every other component is considered to be outside of the system for which conservation of energy is checked.
  When computing an open system by setting openSystemConservationOfEnergy=true these heat flow rates are not taken into account because they are assumed to flow between components that are both within the bounds of the system. The user then needs to choose how large the system is and he should make sure that all heat flow rates entering the system are added to sim.Qgai.Q_flow and that all internal energy of the system is added to sim.E.E.
• The default latitude and longitude, which are read by the TMY3 reader, can be overwritten. This should only be done if a custom weather data reader instead of the TMY3 weather data reader is used.

TMY3 weather data files

Interzonal airflow

IDEAS supports several levels of detail for simulating interzonal airflow and air infiltration, which can be selected by setting the value of the parameter interzonalAirFlowType. By default, interzonalAirFlowType = None and a fixed n50 value is assumed for each zone. The corresponding fixed mass flow rate is pushed into (with ambient properties) and extracted from each zone model. In practice, air infiltration however depends on the wind pressure and occurs only for zones that have an exterior/outer wall or windows.

The other interzonalAirFlowType options model this effect in more detail. By default, the OuterWall and Window leakage coefficients are computed using the zone n50 values. The volume and n50 value of each zone are used to compute the total nominal air infiltration at 50 Pa pressure difference. The total exterior wall and window surface area are used to compute an average air leakage coefficient (q50 value) such that this total air infiltration is obtained at 50 Pa pressure difference. Using these coefficients and the static wind pressures, a flow network is configured that computes the mass flow rates through each wall and window. When a custom q50 value for a wall or window is known, it can be assigned by the user using the parameters use_custom_q50 and custom_q50. The algorithm considers these q50 values as known and recomputes all remaining q50 values such that the n50 value is reached. In a similar way, the total n50 value for one zone can be forced by using the zone parameters use_custom_n50 and n50. In this case, only the remaining zones contribute to the total building air leakage, which is subsequently attributed to the surfaces of only those zones. When use_custom_q50=false, n50 is ignored and sim.n50 is used instead for this computation. I.e., the whole building is assumed to have the n50 value sim.n50 except for zones where use_custom_q50=true.

In case interzonalAirFlowType=OnePort then one port is used to model the air exchange through each surface and through cavities in internal walls (open doors). When interzonalAirFlowType=TwoPorts two ports are used, which increases the level of detail at the cost of having to solve a more complex flow network. The second port e.g. allows more detailed modelling of bidirectional flow through cavities (e.g. open doors) using two flow paths instead of only modelling the total flow through a single flow path. The two-port option is still under development.

When setting unify_n50=true in the SimInfoManager while interzonalAirFlowType=None, the n50 values are automatically redistributed across the zones but instead of using pressure-driven flow, a fixed infiltration flow rate is assumed. While this implementation is more detailed and comes at no added computational cost, it is disabled by default for backward compatibility reasons.

Revisions

• April 16, 2021 by Filip Jorissen:
  Changed the default weather file to Brussels.mos and revised the documentation accordingly. See #1209 for more details.
• June 30, 2020 by Filip Jorissen:
  Overridable assignments of variables of PartialSimInfoManager. See #1148
• November 28, 2019 by Ian Beausoleil-Morrison:
  Make wind direction available on WeaBus. See #1089
• January 21, 2019 by Filip Jorissen:
  Improved documentation by adding weather data reader reference and more TMY3 file examples. This is for #956.
• June 7, 2018 by Filip Jorissen:
  Overwriting TSky, Va and Fc from the extends clause such that they can be overwriten again in BESTEST SimInfoManager. This is for #838.
• June 14, 2015, Filip Jorissen:
  Added documentation