6.2 Localization/Climate

Selecting a Climate Data Set

See Section 6.1.2.

Download and Save a PHIUS+ Climate File or PHIUS+ Climate XML Database

See Section 6.1.2.

6.2.1 Localization

To Upload a PHIUS+ Climate File into WUFI Passive

Select “User Defined” from the dropdown list, click the “Browse” button, and search for the saved climate file. Change the file type in the bottom right hand corner to “Excel (.xls)” if need be. Or, complete a one-time download of the climate database XML file to your WUFI Passive database. This can be done by selecting “Database”, then selecting the drop down menu to “Import from XML File”. These files are also available on the PHAUS Member Resources page. After this import, you will be able to browse your WUFI Passive database to select a climate dataset for your new project.

*Please note climate data import is not available in the free version of WUFI Passive; in this version the climate data must be input manually. See guidance below, Section 6.2.1.1.

About the Design Temperatures in the Climate Data

A super-insulated structure responds more slowly to outside conditions, so the peak loads are moderated. The static mode calculation does also assume a slightly wider comfort range on the inside, 68-77 F instead of for example the Building America default 71-76 F, and similarly, the reason for this is that the inside surface temperatures should be more stable, so the air temperature can vary a bit more and still be comfortable, because the radiant temperature of the surfaces varies less.

We recommend against taking the passive mode design temperatures and using them in an ACCA manual J calculation, but rather run each method on its own terms and compare the bottom line Btu/h results.

Altitude Building: The altitude of the project site must be input. Site altitude may be verified using Google Earth.

PHIUS recommends locating the project site on Google Earth, placing a ‘marker’ on the site at ground level, and providing a screenshot verifying site altitude. This should be uploaded in the Site Plan/Shading folder.

Time Zone: This entry is required for the dynamic shading calculation. Use standard time, not daylight. 

• Eastern Standard Time: UTC -5 
• Central Standard Time: UTC -6 
• Mountain Standard Time: UTC -7 
• Pacific Standard Time: UTC -8 
• Alaskan Standard Time: UTC -9

Ground Thermal Conductivity: In heating dominated climates, this value may not be lower than 0.833 (BTU/hr.ft.F), and should usually be left at the default of 1.1558 (BTU/hr.ft2 .F). For thermal resistance, this is equivalent to no more than 0.1 R/in (hr.ft2 .F/BTU.in).

6.2.1.1 Entering climate data into WUFI Passive Free

6.2.2 Space Conditioning Target Data

Use the PHIUS+ 2018 Target Calculator. Two calculation methods are possible: 

• CALCULATOR method should be used for certification and is based on Envelope-to-Floor Area ratio. 
• ESTIMATOR method approximates Envelope-to-Floor Area ratio based on floor area alone. This should only be used to get quick estimated targets if building envelope area is unknown.

Envelope/iCFA: Envelope area divided by interior conditioned floor area (iCFA) Valid range is

Occupancy (ft2/person): Interior conditioned floor area (iCFA) divided by total occupancy in the building

For residential buildings, the calculations above are straight-forward.

For non-residential buildings, two different occupancy values should be used to determine space conditioning criteria. Therefore, the calculator should be filled out twice with varying occupancy.

Annual Heating/Cooling Demand: Calculate the average occupancy (OccAvg) for the building over all space types according to expected schedules. That average occupancy should then be divided by 0.688 to determine occupancy for the criteria calculator (Occ). Occ = OccAvg / 0.688

Peak Heating/Cooling Load: Use the maximum occupancy.

6.2.3 Source Energy/CO2-Factor

Source Energy Factor for Grid Electricity

The source energy factor for the grid electricity mix in the U.S. is aligned with Energy Star Portfolio Manager. It is different from that of Europe. Use the national average value for certification, regardless of regional differences.

• USA: 2.8 
• Canada: 1.96

This policy forestalls the tendency for “rebound effect” - of building designers taking advantage of locally “cleaner” grids to use more energy, and instead, in effect, shares that benefit with designers in “dirty grid” regions. This is consistent with the idea that with the current fossil-dominated primary fuel mix, energy impact translates into atmosphere impact.

© 2021 Passive House Alliance. All Rights Reserved.