6.3 PH Case – Above Green

6.3.1 PH Case - General

The interior temperature thresholds for PHIUS+ Certification are 68F and 77F. Please contact PHIUS if the program of the project requires a different temperature set point.

Indoor Temperature defined on this tab is the ‘heating setpoint’, 68F should be used.

6.3.1.1 Occupancy and Internal Heat Gains

For residential projects, model occupancy as the # of bedrooms + 1. This is per unit if there are multiple units.

A bedroom is defined as per RESNET: "A room or space 70 square feet or greater, with egress window and closet, used or intended to be used for sleeping. A "den." "library," "home office" with a closet, egress window, and 70 square feet or greater or other similar rooms shall count as a bedroom, but living rooms and foyers shall not."

Internal heat gains are set “calculated”, rather than using a default value by building type.

6.3.1.2 Non-permanent occupants in multifamily buildings: Visitors and Workers

Source Energy Allowance:

Workers: Non-Resident workers such as office workers, senior/medical service workers, etc. will add to the planned occupancy load of the building. Schedules and number of workers should be summed and equated to full time occupants. For example, 3 workers that work 8 hours/day each can equate to 1 full time occupant. The number of equivalent full-time workers can be added to the residential occupancy, and given the residential source energy allowance per person.

Visitors: If the building includes designated spaces that serve the residents as well as outside visitors, the commercial building source energy allowance per square foot should be applied to those spaces.

Internal Heat Gains + Energy Use:

Workers: By adding full time equivalent occupancy for workers into the total occupancy count, internal heat gains and other energy use is appropriately accounted for with no additional input.

Visitors: Depending on the nature of the typical visits (games, dinner, etc), the appropriate energy use of the visitors should be estimated and documented for pre-certification design review.

6.3.1.3 Number of Units and Floors

Number of Units: This is used to calculate the reference quantity for refrigerator and freezer entries, as well as calculating the DHW tap openings per year.

Residential: The total number of residential units should be used. At minimum, a ‘unit’ includes a kitchen, bedroom/living space, and bathroom.

Non-Residential: Enter 1.

Number of floors: The number of floors should be entered. This is used to determine: .

Air-tightness allowance adjustment, if applicable.
Number of floors to be used for the DHW distribution losses when using ‘floor method’.

6.3.2 PH Case - Additional Data

Overheating temperature threshold: This entry is the cooling setpoint. For most cases, 77F should be used for certification.

Fresh Air Per Person: 18 cfm for residential, 9-12 cfm for school and daycare, 35 cfm for sports halls.

Hot water tap-openings per person per day: Defines how many times each DHW tap is opened per person, per day. Used to calculate DHW distribution losses only when using ‘Simplified Individual pipes’ method is for DHW individual pipes.

Residential: This entry will not apply for PHIUS+ 2018 projects. DHW Distribution calculation method cannot be ‘Simplified Individual pipes’ for pre-certification.
Non-Residential: A user defined value may be input here based on total occupants assumed on an average day in the building, the total number of tap openings, and

Infiltration/Airtightness: Per Section 3.2

For buildings of five stories and above that are also of noncombustible construction:

q50 <= 0.080 CFM50/ft2 or q75<= 0.100 CFM75/ft2 of gross envelope area

For all other buildings:

q50 <= 0.060 CFM50/ft2 or q75<= 0.080 CFM75/ft2 of gross envelope area

Gross envelope is measured at the exterior of the thermal boundary, the same as for the energy model, and includes surfaces in contact with the ground.

Envelope airtightness at 50 Pa: PHIUS recommends entering the maximum limit for the building here. A lower value may be used to meet space conditioning targets, but the designer must acknowledge that the lower value must be met in the field in order for the project to pass at final certification.

Non-Combustible Materials: Check this box if the building is of non-combustible construction. If this box is checked, and the building is 5 stories or greater (input on PH Case>General), the ‘target’ airtightness will be adjusted in the model and report.

Example project conversion from cfm50/ft2 to ACH50:

Total envelope area 6958 ft2

Net volume 19387 ft3

6958 ft2 * (0.05 ft3 /min)/ft2 ) * (60 min/hr.) * (1/19387 ft3 ) = 1.08 ACH50

Maximum Humidity Ratio (if dehumidification is planned)

The default value is 0.012 lbw/lba; it is not to be changed for PHIUS+ Certification. It is the upper limit for humidity levels according to the comfort standard ASHRAE 55-2004. This is essentially a humidity set-point. At 77 F and a 0.012 humidity ratio, it corresponds to approximately 60% relative humidity.

Domestic Hot Water Use Per Person

Residential: 6.6 gal/person/day
- Default should be used for certification. Higher values may be accepted.
Non-residential: 3.2 gal/person/day
- The default above will not fit for all non-residential projects. The entry may vary from the default if supporting documentation/calculation is provided and approved by PHIUS.

This input pertains to showers, hand-washing, and shaving. Laundry and dishwashing is separate from that, and calculated with the appliance entries. If there is no dishwasher, consider adding extra gallons to this daily value.

Remember, these are “hot gallons” (140 F). It calculates the energy to raise the water from the incoming water temperature (default 50 F) to 140 F, a 90 F rise. When mixed down to a temperature a person would actually want to shower under, it goes almost twice as far in terms of volume.

Cold Water Supply/Incoming Temperature

If this input is left blank in WUFI Passive, it will calculate using an average annual ground temperature.

A user defined entry may be used if supporting documentation is submitted to confirm the new groundwater temperature. The adjusted groundwater temperature generally should not exceed the average ambient air temperature for the project’s climate.

6.3.3 PH Case - Foundation Interface

Up to 3 different foundation interface connections can be defined. These determine reduction factors to be applied to components with ‘Ground’ assigned on the Outer Side.

Floor Slab / Floor Ceiling Area

For heated basements, only include the interior floor area. For all other basement conditions, include the entire floor area calculated to the exterior of the thermal boundary.

Floor Slab Perimeter

For heated basements, only include the interior perimeter. For all other basement conditions, include the entire (exterior-adjacent portion of the) floor slab perimeter measured at the exterior of the thermal boundary.