6.1 Getting Started – Above Green

6.1.1 Accepted Modeling Software

For PHIUS+ 2018:

WUFI Passive: 3_2_0_1 or later*

WUFI Passive Free: 3_2_0_1 or later *

3_1_1_25 accepted for PHIUS+ 2018 pilot projects, or on a case-by-case basis.

6.1.1.1 General Recommended WUFI Passive Settings

Options	General	Dimensions, visualized geometry	Outer, extern partitions not included.
Options	Usability	Tool tips	Check all boxes to ensure the proper hover-over hints are visible.
Options	Usability	Data Recovery	Turn this on to auto-save projects.
Options	Usability	Comments	Use this to save note within each screen of your project file. Helpful for colleague, reviewer, personal note, etc
Options	Usability	Show edit icons in tables	Select to view cells with built-in calculators. Will appear with […].
Options	Usability	Show project/case in footnotes	Select to include case name in footer of printed results reports.
Options	Passive	Default Certificate Criteria	Set to PHIUS+ 2018

6.1.1.2 WUFI Passive Online Tutorials

Free online tutorials can be found here: http://www.phius.org/phius-certification-for-buildingsproducts/wufi-passive-tutorials

6.1.1.3 Project File Versions

Older project files can always be opened in newer version of the software, but newer files generally cannot be opened in older versions.

Sometimes*, a project file can be opened in a previous version of WUFI Passive. To do this, save the file type as ‘XML’ in the newer version WUFI Passive, then, open the XML file in the older version.

i.e. A project file created in WUFI Passive 3_2_0_1 cannot be opened in 3_1_1_0.

A project file created in WUFI Passive 3_1_1_0 can be opened in 3_2_0_1.

*It is not guaranteed that files created in “intermediate” or test versions of WUFI Passive can be opened in future release versions.

6.1.1.4 Dynamic modeling in WUFIplus

Though not required for certification, consider also doing dynamic modeling (WUFI Plus) when:

Cooling and/or moisture loads are high.
Heating is discontinuous (during the heating period).
Occupancy and indoor conditions vary considerably.
Comfort and overheating should be assessed.

If dynamic modeling seems called for, PHIUS suggests running a 3-zone dynamic model as a comfort analysis using WUFI Plus (WUFI Passive dynamic side), or another dynamic energy model. The 3 zones would be coldest room, warmest room, rest-of-building. There are two possible approaches – one is to set the heating and cooling system capacities very high, and look for the persquare-foot differences in the heating and cooling loads among the zones. The other is to limit the system capacities and look for failure to maintain the desired interior temperature set-points.

6.1.2 Climate Data

Must be approved by PHIUS for each project.
It is important to choose the correct dataset, especially given that a project’s spaceconditioning performance targets vary by location.
PHIUS has generated 1000+ climate datasets for locations around the United States; they are available as individual XML database import files for each state, as well as a single XML file for the entire United States. These datasets are available free to PHAUS members and can be downloaded from the PHAUS Member Resources page.
A custom data set is required for a project location when the closest existing data set is more than 50 linear miles and >400’ different in elevation from the project location.
- Project locations even within the parameters above might benefit from custom climate data.
- Please refer to the PHIUS blog posts “Climate Data – When to Request a Custom Dataset” and “Climate Data and PHIUS+ 2015" for more information.
- The cost of a custom climate data set is $75 and may be purchased here: http://www.phius.org/software-resources/wufi-passive-and-other-modelingtools/climate-data-sets
If project is within 50 linear miles and within 400 feet difference in elevation of an existing climate data set, you must use the PHIUS+ space conditioning targets associated with the existing data set. However, you can order custom climate data if you'd like to.

6.1.3 Energy Model Defaults

The accepted software versions agree on default input values for several input parameters. Unless otherwise noted below, these values should be used in the energy model for certification. These values (and the way they are calculated) may be updated in the future to coincide with research and best practices.

6.1.4 Energy Model Inputs Requiring Additional Documentation

Ground Thermal Resistivity > 0.1 hr.ft2 .F/BTU.in.
Window frame-to-wall psi value < 0.015 BTU/hr.ft.F Subsoil heat exchanger efficiency > 60%.
Air change rate for window ventilation; see Section 6.7.3.
Solar fraction for hot water – expert/specialist calculation recommended if greater than 65% estimated to be covered by solar in WUFI Passive model.

6.1.5 External Calculators & Protocol Documents

Many external calculation methods and protocol documents are developed as new modeling situations arise. Eventually, these calculation methods and protocol are built in or implemented into the WUFI Passive energy modeling tool. External calculators may be used in the interim.

Always download the latest version of the protocol documents on the Calculators & Protocols page.

6.1.6 WUFI Passive Cases

WUFI Passive allows for quick creation of multiple ‘cases’ within a single project file. Cases are generally created by duplicating a previous case. This can be used to compare alternate designs and provides direct result comparison. Cases can contain varying geometry, and a new geometry file can be imported into a duplicate case.

For Mixed-Use projects, it is helpful to import the whole building as two zones (residential and nonresidential). Then, one case can cover the residential portion as the ‘active’ or ‘simulated zone’, and the second case can cover the non-residential portion as the ‘simulated zone’. This keeps the entire building in one WUFI Passive model.