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Single-Family Attached

Consider the highlighted “Single-Family Attached” building footprint with the following high-level URBANopt GeoJSON inputs:

  • 2 stories above ground
  • slab foundation
  • vented attic
  • 4 living units
  • no rear units


The number of living units are used to determine the position (i.e., horizontal location) of individual living units contained in the building. By determining the position of individual units relative the whole building, types and boundary conditions of surfaces (e.g., adiabatic) can be stored in the HPXML.

Example 3D renderings for a single unit from the building is shown below. This unit is designated as having a “Right” horizontal location (when viewing from the front). You can see outside boundary conditions of “Outdoors” on one facade, and “Adiabatic” on the opposite facade.

single_family_attached single_family_attached

Note that the footprint of the modeled unit is always rectangular even though the GeoJSON footprint may not be. See Other Assumptions for more information.

For each unit of the building, an HPXML and OSM model is constructed. These OSM models are merged into a single OSM model, as shown below.


Modeling Notes

  • “Single-Family Attached” home models may be heated only, cooled only, or both heated and cooled.
    • Partial Conditioning: heating and cooling may be applied to just a portion of the living space of the home or to the entire living space. Representation of partial conditioning of the living space of a home is accomplished by adding ideal air load system to heat and cool the unconditioned portion of the living area. In this situation, district heating or cooling loads may show up in end uses for the home.
    • Undersized Mechanical System: District heating or cooling loads may also show up in end uses when a designed mechanical system cannot meet the load required to maintain thermostat temperatures. An example would be an evaporative cooling system in a hot humid climate.
    • For both the partially conditioned and undersized examples, it is possible for reporting or post processing to filter out these unintended district heating and cooling loads.
  • It is important to know, that unlike the commercial models that will result in unmet heating or cooling hours, the residential models will not have any unmet heating or cooling hours. To understand how the HVAC system is conditioning for “Single-Family Attached” home models, users should look at district heating and cooling loads.

GeoJSON Schema

The URBANopt GeoJSON schema differentiates between sets of required and optional fields for “Single-Family Attached” residential buildings:

Required fields:

Field Type Enums Notes
floor_area number   Total conditioned floor area.
footprint_area number   First floor conditioned floor area.
number_of_stories_above_ground integer    
number_of_stories integer   Includes foundations.
number_of_residential_units integer    
number_of_bedrooms integer   Must be > 0.
foundation_type string (1) slab
(2) crawlspace - vented
(3) crawlspace - unvented
(4) crawlspace - conditioned
(5) basement - unconditioned
(6) basement - conditioned
(7) ambient
attic_type string (1) attic - vented
(2) attic - unvented
(3) attic - conditioned
(4) flat roof
Stories > 1 for conditioned attics.

Optional fields:

Field Type Enums Notes
roof_type string (1) Gable
(2) Hip
NA when attic type is flat roof.
occupancy_calculation_type string (1) asset
(2) operational
number_of_occupants integer   For operational calculations.
system_type string (1) electric resistance
(2) furnace
(3) boiler
(4) central air conditioner
(5) room air conditioner
(6) evaporative cooler
(7) air-to-air heat pump
(8) mini-split heat pump
(9) ground-to-air-heat-pump
heating_system_fuel_type string (1) electricity
(2) natural gas
(3) fuel oil
(4) propane
(5) wood
template string   See Customizable Template
hpxml_directory string   Relative to xml_building. Most required fields are then optional.

An example “Single-Family Attached” building feature snippet is shown below.

      "id": "17",
      "name": "Residential 4",
      "type": "Building",
      "building_type": "Single-Family Attached",
      "floor_area": 18320,
      "footprint_area": 9160,
      "number_of_stories_above_ground": 2,
      "number_of_stories": 2,
      "number_of_bedrooms": 6,
      "foundation_type": "slab",
      "attic_type": "attic - vented",
      "system_type": "Residential - furnace and room air conditioner",
      "heating_system_fuel_type": "fuel oil",
      "number_of_residential_units": 4,
      "template": "Residential IECC 2015 - Customizable Template Sep 2020"

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