Design basis
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Used to display key design parameters considered for
the ASHRAE RTS calculation. Selecting Design basis in the selector panel (left)
updates the reports display panel (right), scrolling to the Design basis
display.
-
Location — Displays the project location set for the project in the Properties
dialog box’s
Properties For: Site
panel.
- Design
Day — Displays the day on which the greatest loads are experienced. The design
day is used to compute sun positions and solar gains and to calculate the
hourly outside dry and wet bulb temperatures using the weather database
information for the specified location.
-
External shading is/is not considered — Indicates external shading is or is not
considered. The use of external shading for gains calculations is set in the Default
Manager dialog box’s
Simulation run-time control
panel. If you opt to include external shading, the
calculation will check if each window is shaded by external obstructions at
each hour of the day. Shaded windows will receive diffuse solar radiation only.
- Fins
are/are not considered — Indicates fins are or are not considered. The use of
external shading for gains calculations is set in the Default
Manager dialog box’s
Simulation run-time control
panel.
-
Outside drybulb temperature — Displays the maximum outside drybulb temperature
experienced on the design day. This value comes from the weather profile being
used for the project.
- No
Additional fresh air — Indicates no additional fresh air changes due to forced
fresh air ventilation or opening windows will be conisdered in the calculation
- Rooms
included — Displays the number of rooms included in the calculation.
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Results for room: [Room name]
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For each included room, the peak heat gain and peak
hour will be displayed for the room. The project total loads for all the
included rooms are produced by adding room loads on an hour-by-hour basis for
each of the 24 hours of the design day. The coincident peak hour for all rooms
is that hour which has the maximum coincident load. If fresh air loads are
specified with the design data, these will be included in the project total
loads.
- Sun
Time — Displays the hour of the peak design day from 1 through 24.
-
Outside temp. — Displays the outside temperature for each hour of the design
day. The outside temperature is derived from the weather data associated with
the project location.
-
Envelope — Heat flow through each exposed wall is computed for each hour of the
design day from the wall area, U value, cooling and load temperature
differences. The temperature difference value is automatically included in the
calculation, and a correction is made for wall color, inside temperature and
average outside temperature. The wall color correction is carried out using the
wall absorption coefficient to solar radiation.
- Glazing
— For each window, and for each hour of the design day, the maximum solar gain
on the sunlit portion is determined, and the actual sunlit and shaded areas of
glass are computed from the window dimensions and the side and top projection
distances. Cooling load factors for each hour of the day are applied, depending
on whether interior shading is specified or not. The shading coefficient is
incorporated for all window types. For the glass in the shade, the wall cooling
load factor for north facing, shaded walls is used. The thermal weight used is
that specified for the room. Orientations are rationalized from angles to the
nearest ASHRAE orientation (N, NNE, NE, etcetera). Rooflights are treated in
exactly the same way as windows, except that they are assumed to be unshaded
and subjected to radiation for a horizontal surface.
-
Infiltration — The infiltration heat gain for each hour of the design day is
found from the room volume, the infiltration air change rate, and the inside
and outside temperatures. Infiltration gains are separated into their sensible
and latent components.
-
Internal — Gains from internal sources for each hour of the design day are
determined. Internal gains are separated into their sensible and latent
components.
-
Outside air — For each hour of the design day, outside air may be introduced
locally to rooms, in which case it will affect the room load. Outside air from
the central plant will form part of the supply air and will be a load on the
central plant as well. Conditioned primary air will be supplied at the defined
supply temperature, with optional supply humidity control. Conditioned primary
air will affect both room loads and central plant loads. If conditioned primary
outside air is specified and this outside air requires heating at the central
plant, when the building requires cooling (or vice versa), then the outside air
heat load will be excluded from the central plant loads. Outside air gains are
separated into their sensible and latent components.
- Total
load — Displays the sum of all the loads in the room for each hour of the
design day.
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Internal Loads for room: [Room] at Peak Time: [Peak
hour]
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Loads from internal sources experienced at the peak
time are broken down to individual load components, and listed on the following
table.
-
Internal Loads — Sources of internal loads are listed separately:
-
People – Defined by the room’s expected occupancy or number of people. This is
set in the Properties
dialog box’s
Properties For: Room
panel’s Design data sub panel.
-
Lighting – Defined by the product of the lighting sensible load and the
lighting schedule value for the design day peak hour.
-
Lighting % to RA – Defined as the resulting load from the percentage of
lighting energy that is dissipated as heat. Lighting systems convert only a
fraction of their electrical input into useful light output. This heat must be
removed by the building’s cooling system to ensure the comfort of its
occupants.
-
Casual gains – Defined as the gains for the selected room at peak time which
are due to lighting, people and the casual gain during occupancy.
-
Additional gains #1& #2 – Gains such as infiltration from unconditioned
spaces through partitions are considered. These are set in the Properties
dialog box’s
Properties for: Room
panel’s Additional Gains sub panel.
- [Table
second column] — Displays the total area occupied by each internal load
component.
- Per
Unit Cooling — Displays the Per Unit Cooling load generated by each internal
load component.
- Room
Sensible Cooling — Displays the Room Sensible Cooling load generated by each
internal load component.
- Return
Air Sensible Cooling — Displays the Return Air Sensible Cooling load generated
by each internal load component.
- Return
Latent Cooling — Displays the Return Latent Cooling load generated by each
internal load component.
- Room
Sensible Heating — Displays the Room Sensible Heating load generated by each
internal load component.
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Envelope Loads for room: [Room] at Peak Time: [Peak
hour]
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Envelope loads from each room element experienced
at the peak time are broken down to individual load components, and listed on
the following table.
-
Category — Displays the surface element types that make up the room, including
exposed walls, partitions, windows, doors, ceilings, floors and roofs.
- Area —
Displays the total area occupied by each envelope load component.
- Per
Unit Cooling — Displays the Per Unit Cooling load generated by each envelope
load component.
- Room
Sensible Cooling — Displays the Room Sensible Cooling load generated by each
envelope load component.
- Return
Air Sensible Cooling — Displays the Return Air Sensible Cooling load generated
by each envelope load component.
- Return
Latent Cooling — Displays the Return Latent Cooling load generated by each
envelope load component.
- Room
Sensible Heating — Displays the Room Sensible Heating load generated by each
envelope load component.
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Infiltration Loads for room: [Room] at Peak Time:
[Peak hour]
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Infiltration loads from each room element
experienced at the peak time are broken down into heating or cooling
components, and listed on the following table
-
Category — Displays the load type (Cooling and Heating).
-
Airflow — Displays the airflow required for the load.
- Per
Unit Cooling — Displays the Per Unit Cooling load generated by each envelope
load component.
- Room
Sensible Cooling — Displays the Room Sensible Cooling load generated by each
envelope load component.
- Return
Air Sensible Cooling — Displays the Return Air Sensible Cooling load generated
by each envelope load component.
- Return
Latent Cooling — Displays the Return Latent Cooling load generated by each
envelope load component.
- Room
Sensible Heating — Displays the Room Sensible Heating load generated by each
envelope load component.
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Total Loads at hour: [Peak hour]
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Displays the total of the Internal, Envelope, and
Infiltration loads at the peak time for each room.
- Room
Sensible Cooling — Displays the total Room Sensible Cooling load for the room.
- Return
Air Sensible Cooling — Displays the total Return Air Sensible Cooling load for
the room.
- Return
Latent Cooling — Displays the total Return Latent Cooling load for the room.
- Room
Sensible Heating — Displays the total Room Sensible Heating load for the room.
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Project total results
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For the sum of all included rooms, the peak heat
gain and peak hour will be displayed. The project total loads are produced by
adding room loads on an hour-by-hour basis for each of the 24 hours of the
design day. The coincident peak hour for all rooms is that hour which has the
maximum coincident load. If fresh air loads are specified with the design data,
these will be included in the project total loads.
- Sun
Time — Displays the hour of the peak design day from 1 through 24.
-
Outside temp. — Displays the outside temperature for each hour of the design
day. The outside temperature is derived from the weather data associated with
the project location.
-
Envelope — Heat flow through each exposed wall is computed for each hour of the
design day from the wall area, U value, cooling and load temperature
differences. The temperature difference value is automatically included in the
calculation, and a correction is made for wall color, inside temperature and
average outside temperature. The wall color correction is carried out using the
wall absorption coefficient to solar radiation.
-
Glazing — For each window, and for each hour of the design day, the maximum
solar gain on the sunlit portion is determined, and the actual sunlit and
shaded areas of glass are computed from the window dimensions and the side and
top projection distances. Cooling load factors for each hour of the day are
applied, depending on whether interior shading is specified or not. The
shading coefficient is incorporated for all window types. For the glass in the
shade, the wall cooling load factor for north facing, shaded walls is used. The
thermal weight used is that specified for the room. Orientations are
rationalized from angles to the nearest ASHRAE orientation (N, NNE, NE,
etcetera). Rooflights are treated in exactly the same way as windows, except
that they are assumed to be unshaded and subjected to radiation for a
horizontal surface.
-
Infiltration — The infiltration heat gain for each hour of the design day is
found from the room volume, the infiltration air change rate, and the inside
and outside temperatures. Infiltration gains are separated into their sensible
and latent components.
-
Internal — Gains from internal sources for each hour of the design day are
determined. Internal gains are separated into their sensible and latent
components.
-
Outside air — For each hour of the design day, fresh air may be introduced
locally to rooms, in which case it will affect the room load. Outside air from
the central plant will form part of the supply air and will be a load on the
central plant as well. Conditioned primary air will be supplied at the defined
supply temperature, with optional supply humidity control. Conditioned primary
air will affect both room loads and central plant loads. If conditioned primary
outside air is specified and this outside air requires heating at the central
plant, when the building requires cooling (or vice versa), then the outside air
heat load will be excluded from the central plant loads.
- Total
load — Displays the sum of all the loads in all rooms for each hour of the
design day.
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