How to Install HAP Software: The Ultimate Guide for Engineers

What Is HAP Software Used For in HVAC Design?

Two engineers can model the same office in HAP and arrive at different cooling capacities. The difference may be a glazing assumption, an occupancy schedule or the way outdoor air is treated. Understanding those decisions is what turns software operation into HVAC design.

This guide follows the work from architectural inputs to load reports, airflow checks and energy comparisons. The 16 images come from Carrier’s official documentation: eight HAP v6.4 software and export images, six foundational workflow screenshots from v6.0, and two from v6.2. Every caption identifies the source version; earlier images explain established workflows and may differ from your installed interface. They show Carrier demonstration projects, separate from the illustrative calculations below. Use “Enlarge image” to inspect each original screenshot.

TL;DR

What Is HAP (Hourly Analysis Program) Software?

Carrier HAP software helps HVAC consultants, design engineers and energy analysts turn building information into design calculations. Its typical commercial applications include offices, schools, hotels and hospitals.[1]

Think of its model as a set of engineering assumptions: where the building is, how it is constructed, when people occupy it and how its HVAC systems operate. An attractive 3D model is useful, but those assumptions determine whether the calculation represents the project.

The five levels of a HAP design model

Keep five concepts separate as you work. The building describes physical geometry. The space model adds thermal characteristics and use. Zones describe how spaces are controlled. Air systems describe how conditioned air reaches those zones. Plants describe the central equipment serving systems that use shared heating or cooling production. Not every project needs every type of plant.

For example, an office with several FCUs and a treated outdoor-air supply is not one undifferentiated cooling load. Each occupied zone has its own demand; each terminal must handle its assigned duty; the outdoor-air equipment has a separate treatment task; and a shared chilled-water plant sees the combined duty reaching it at each time. Consistency between these levels matters more than matching a familiar total tonnage.

What HAP does not finish for the engineer

A sizing calculation is an input to equipment selection. The design still needs a check against manufacturer performance at the actual entering-air conditions, water temperatures or outdoor temperature, as applicable. It also needs duct and pipe layouts, pressure-loss calculations, control decisions, installation clearances and coordinated drawings.

Do not read an airflow result as a completed duct design or a coil capacity as a selected machine. The calculation tells you the duty to investigate. The final selection must show that real equipment can deliver that duty under the proposed operating conditions.

What HAP Software Is Used For

Cooling and heating load calculation

Cooling-load analysis tracks changing heat gains from the envelope, solar exposure, occupants, lighting and equipment, alongside the effect of outdoor air. Heating design evaluates the capacity required under the selected winter conditions. HAP provides hourly design-day profiles and separate space, zone and system reports.[3]

A west-facing meeting room illustrates why timing matters. Afternoon sun and a full room may coincide, while another room peaks earlier. Adding every room’s individual maximum can overstate the simultaneous system demand. Check when the peaks occur before using them to size shared equipment.

Annual energy modeling and cost comparison

HAP also simulates a year of operation using hourly weather, schedules and equipment behavior. Energy consumption and utility rates support comparisons between alternative designs.[1] Carrier’s sample reports separate annual costs, component energy use and hourly performance.[3]

Do not multiply cooling capacity by 8,760 and call it annual electricity. That ignores changing demand, operating hours and efficiency. For a fair comparison, hold the building, occupancy and comfort assumptions constant unless changing one is the purpose of the study.

Key Features of HAP Software

Graphical building modeling

In HAP v6, engineers can import floor-plan images, establish scale and orientation, trace spaces and create a 3D building model. This makes geometry easier to inspect. A wrongly scaled plan still needs correction; automation does not validate the drawing for you.[2]

ASHRAE-based calculations and system sizing

HAP v6 uses the ASHRAE Heat Balance load method and integrates the EnergyPlus calculation engine.[2] Its system-based sizing workflow supplies airflow and component-sizing information for the selected HVAC arrangement.[1]

Reports that support engineering review

Start with the Air System Sizing Summary, Zone Sizing Summary and Ventilation Sizing Summary. Then investigate unusual results through hourly profiles, heat-balance breakdowns and system psychrometrics. Carrier publishes sample reports you can examine before building your first project.[3]

How to Get Started with HAP

HAP software download: trial or licensed access?

For a HAP software free download, begin with Carrier’s official trial request. Its published offer is a 60-day trial, with installation instructions supplied after requesting access.[4] Continued use requires appropriate licensing; course enrolment should not be assumed to include a permanent licence.

Use Carrier’s official software-download page for a licensed installer. As checked on 24 September 2026, it lists HAP v6.4 and a legacy HAP v5.2 download, both requiring a licence key.[5] Before choosing the older release, confirm your employer’s project requirements and the version used in your training.

What changes when an existing project is opened?

HAP v6.4 converts earlier v6 projects. Save the converted file separately and rerun its calculations; it cannot subsequently be opened in v6.3.[8] Keep the original file alongside the issued reports so a reviewer can distinguish an input change from a software-version change.

HAP Software Tutorial: From Inputs to Reviewed Reports

Start with a small office containing a perimeter workspace, meeting room and internal room. Keep a written input register with a source for every important assumption. The sequence below explains the decisions to make, rather than prescribing values that may be wrong for your building.

1. Establish the design basis and weather

Record location, project units, indoor temperature and humidity criteria, operating hours and applicable ventilation requirements before entering room data. Obtain the current architectural drawings, envelope specification, glazing schedule, occupancy brief and equipment list. Flag missing information as an assumption requiring confirmation.

Design weather supports equipment sizing; simulation weather supports annual analysis. Do not treat a city's average summer temperature as a peak design condition. Also check the station's elevation and whether it reasonably represents the site. A coastal city and an inland location can require different moisture treatment even when their dry-bulb temperatures look similar.

Keep the project's unit system visible in your input register. Mixing W/m² with W/ft², or treating an airflow in L/s as m³/h, can overwhelm the effect of any sophisticated calculation method. Note that Carrier's screenshots here use Imperial units; they are examples, not prescribed settings for an Indian project.

Write down who approved the indoor criteria. A lower room temperature or tighter humidity requirement can alter airflow, coil duty and control needs. A calculation made at one setpoint should not quietly be used to select equipment for another. Likewise, identify whether a special room has process or continuous-operation requirements that differ from the rest of the building.

Use the map to understand where the station sits relative to the building. Then review the station data before accepting it. Distance alone is a weak selection rule: elevation, coastal influence and urban surroundings can make the nearest station less representative. Record the selected station and the design criteria in the calculation notes so another engineer can reproduce the basis.

A weather design percentage describes the frequency associated with a design condition; it is not a percentage to multiply into the cooling capacity. Agree the required design basis with the project team. If a critical space needs a different basis from a general office, identify that requirement explicitly instead of applying an undocumented allowance to every room.

2. Build the geometry and verify each level

Scale the imported floor plan against a known dimension, confirm north and trace the relevant spaces. Record which surfaces face outdoors, conditioned rooms, unconditioned rooms or ground. An internal partition incorrectly treated as an exposed wall changes the thermal problem.

Read the model vertically as well as horizontally. A roof over one wing may sit beside another wing's occupied floor. Check stairs, shafts and double-height rooms against the sections, not only the plan. When repeating a floor, verify its external exposure rather than assuming every copied room has identical conditions.

Read this view as a geometry check. Each modeled space should correspond to a deliberate thermal boundary. Begin with one known drawing dimension and compare another dimension in the perpendicular direction. A plan that looks correctly aligned can still have the wrong scale, and that error then affects floor area, exposed wall area and area-based internal loads.

Choose consistent room names before duplicating levels. For example, a name that identifies the floor and room makes it easier to compare a HAP result with the drawing and equipment schedule. Check whether a corridor, shaft or service room is conditioned, unconditioned or excluded under the modeling approach; do not let its status be determined accidentally by a gap in tracing.

Rotate the model and compare every elevation with the drawings. Look for misplaced glazing, incorrect floor heights, missing setbacks and roofs that should be partly sheltered by another level. The benefit of this view is that a mistake hidden in a dense floor plan can become obvious in the building shape.

The model is also a useful prompt for reviewing exposure. Two rooms with the same floor area may have very different loads if one sits under a roof or has extensive west-facing glass. A correct visual model is the starting point; construction properties, internal gains and controls still need their own checks.

Using a BIM model through gbXML

Carrier introduced gbXML import in HAP v6.2 to bring building geometry from compatible BIM or CAD workflows into HAP. The source drawing needs complete, closed spaces and a compliant export. The imported model must then be reviewed.[14]

Treat a successful import as the start of checking. Reconcile the number of levels, room areas and openings against the design drawings. Inspect unusual shapes and very small spaces first because these can reveal export problems. Confirm the thermal assignments and operating assumptions separately rather than assuming an architectural model contains a completed load-calculation model.

When architecture changes, keep a record of what changed and which calculation revision uses it. A revised glazing layout may alter cooling demand even if the room names and floor areas remain unchanged. The aim is traceability between drawings, model inputs and issued results.

3. Enter openings, then assign their thermal properties

Window geometry and window thermal performance are separate inputs. Width, height, position and orientation describe the opening. U-value describes heat transfer through the assembly, while solar heat gain coefficient (SHGC) describes admitted solar heat. A correctly drawn window with the wrong thermal properties is still a wrong load input.

Cross-check the opening tags against the architect's window schedule. For repeated windows, review both the dimensions and the total glazing area on each orientation. Include the specified external shading. Treat blinds and occupancy-dependent shading assumptions consistently between the design basis and the modeled operating schedule.

Use this review to separate two questions: does the opening have the right size, and does it have the right construction? Similar-looking windows may use different glass or frames. Record whether the supplied U-value describes the whole window or only the glazing, and resolve inconsistent manufacturer data before applying it throughout the project.

This properties window helps explain why a glass description alone is insufficient. U-value concerns heat transfer driven by a temperature difference. SHGC concerns solar heat admitted through the glazing. Visible transmittance describes visible light transmission. These quantities answer different questions and should not be substituted for one another.

As an illustrative comparison, two windows could have similar U-values but SHGC values of 0.25 and 0.50. Under comparable solar conditions, the second admits substantially more solar heat. That does not mean the whole room's peak cooling load doubles: the room also has people, equipment, ventilation and other heat flows, and its peak depends on timing. Use the example to understand the input, then evaluate the complete model.

4. Check wall, roof and floor assemblies

Choose construction data that represents the specified building. Review material sequence, thickness, insulation and thermal properties. Do not select a familiar library name simply because its overall U-value seems plausible; thermal storage and exposed surface properties also affect the timing of heat transfer.

The screenshot uses a steel-framed assembly. That is not a substitute for a specified masonry wall. For your project, compare the modeled layers with the approved construction detail and check units before accepting the resulting thermal performance.

Distinguish U-value from insulation thickness. U-value represents the assembly's overall thermal transmittance, including the relevant layers and surface resistances. Thickness is only one input. Two assemblies can have similar overall heat transmission but different thermal storage, so a steady-state check alone will not explain every hourly cooling-load difference.

For a simple transmission check, Q = U × A × ΔT. An illustrative wall with U = 0.5 W/(m²·K), area 40 m² and a 10 K air-temperature difference gives 200 W. That is a steady-state check on units and order of magnitude, not a replacement for an hourly wall calculation with solar exposure and thermal storage.

HAP v6.4 adds support for ASHRAE 62.1-2022 and 90.1-2022.[8] The available software options do not decide which standard edition your contract or jurisdiction requires. Similarly, a prescriptive default is not proof that an existing building was constructed that way.

5. Model people, lighting, equipment and schedules

Separate the installed load from its time pattern. A lighting input of 8 W/m² over 200 m² represents 1.6 kW at full use. A 50% operating fraction represents 0.8 kW of lighting input at that hour. It does not mean the immediate cooling load must also be exactly 0.8 kW, because heat storage and the radiant/convective split affect timing.

A schedule name is not evidence that the hourly profile is correct. Review weekday, weekend and holiday operation. Check whether people, lights, plug loads, fans and thermostat settings follow different patterns. An office with cleaners after hours may have lighting and ventilation operation without normal occupancy.

For a meeting room, use its intended occupancy and realistic occupied periods. A low average office density can miss a full-room event. Conversely, running every person and appliance at maximum for every hour distorts an annual energy comparison. Document design-load assumptions separately where they differ from expected annual operation.

People release both sensible and latent heat. Use an activity level appropriate to the room rather than treating a seated office and an exercise room alike. For equipment, distinguish the electrical nameplate rating from the heat actually released into the conditioned space. Establish whether any heat is removed by exhaust, a water circuit or another route.

Keep the assumptions consistent without forcing every schedule to be identical. A server room can operate all night while the office is empty. An AHU may start before occupants arrive. A meeting room may have brief high-density periods. These differences are precisely why a single building-wide on/off schedule can conceal important behavior.

Review the grid in two directions. Across a row, check that one room's area, use and assigned assumptions agree. Down a column, look for a value or assignment that differs unexpectedly from similar rooms. A meeting room given an open-office assumption deserves attention even when the building's total load looks reasonable.

Work from the project brief when accepting defaults. Repetition makes data entry faster, but it can also spread an incorrect assumption to many rooms. Before applying a common input to a group, decide which rooms are genuinely equivalent. Keep specialist rooms separate and note the evidence for their occupancy and equipment gains.

6. Define zones, air systems and outdoor-air treatment

A space is a modeled room or area; a control zone is a group regulated together; an air system serves those zones. Group rooms according to the actual control arrangement, not merely to reduce data entry. A west-facing meeting room and an internal room may have incompatible demand patterns.

Follow the air path. Is outdoor air mixed at an AHU, treated by a dedicated outdoor-air system, or supplied to a room served by an FCU? Assign its cooling and moisture treatment to the equipment that actually performs it. Check for both omission and double counting when coordinating terminal and central equipment.

Define the intended supply-air conditions, fan operation and system control assumptions. Then review whether the resulting airflow is governed by sensible cooling, ventilation, heating or a specified constraint. Avoid forcing a preferred airflow into the model merely to reproduce an earlier rule-of-thumb selection.

Use the colored plan to check which spaces are controlled together. Then compare that grouping with the actual thermostat, terminal unit and duct layout. Rooms served by one AHU do not necessarily belong to one control zone. Conversely, splitting every room into a separate model zone can imply more independent control than the proposed installation provides.

Consider an internal office beside a glazed meeting room. The office may need steady cooling from equipment while the meeting room experiences short peaks from people and sun. If one thermostat controls both, the design must address their different demands. The model should expose that control limitation, not hide it by assuming each room can independently receive its ideal airflow and temperature.

Ventilation and infiltration are different inputs

Ventilation is the intentional outdoor-air supply required by the design. Infiltration is uncontrolled air leakage through the envelope. Neither should be used as a convenient substitute for the other. A building may receive controlled outdoor air while also experiencing leakage, but those quantities need a consistent pressure and operating basis.

For ventilation, confirm the occupancy category, population, floor area and applicable rates. Then check the distinction between the breathing-zone requirement, the zone supply arrangement and the outdoor-air intake required at the system. Carrier's published ventilation example shows why the final intake need not equal a simple unadjusted sum.[10] That legacy example explains report structure; its old standard edition is not a current project prescription.

For infiltration, document the leakage assumption, exposure and hours of application. Do not automatically add a whole-building air-change allowance to every room that already has an outdoor-air allowance. Inspect the physical route and the pressure relationship first. Excessive infiltration can create a misleading load increase, while assuming none without justification can hide a real envelope problem.

Why cooling, airflow and humidity must be checked together

Supply air colder than the room removes sensible heat, but moisture removal depends on its humidity ratio. A unit can satisfy the thermostat while leaving humidity too high. In a humid climate, investigate the coil's dehumidification performance and the outdoor-air treatment instead of treating extra nominal tonnage as a universal solution.

The sensible heat ratio is sensible cooling divided by total cooling for a defined load or process. Always name the boundary: room sensible heat ratio and coil sensible heat ratio are not automatically identical. Outdoor air and system effects can change the balance. This distinction becomes important when comparing a room requirement with a manufacturer's sensible and total capacities.

7. Select reports and interrogate the results

Begin with sizing reports, then open the diagnostic report that answers the question in front of you. A large cooling load calls for an input and heat-balance review; an unexpected airflow calls for checking supply temperature, ventilation and control assumptions. Printing every report is less useful than knowing which one explains the result.

Use the system summary for central equipment and the zone summary for zone-level requirements. Follow up with ventilation sizing and psychrometric information where those determine the selection. Before issuing a capacity, identify its units, sensible/total basis, calculation level and associated design conditions.

HAP v6.4 introduces XLSX design-load exports.[8] A spreadsheet is useful for review, but preserve the original export and record any downstream changes. Values copied into an equipment schedule should remain traceable to the system, zone and calculation revision.

Notice the separation of sensible cooling, latent cooling and time of peak. Read across a row before comparing rooms, and compare peak times before adding loads. The numbers shown are Carrier's example results, not design targets or benchmark loads for your building.

8. Extend the checked design into an energy comparison

After the load model is credible, compare alternatives using consistent weather, envelope, occupancy and comfort criteria. Define equipment efficiency at appropriate operating conditions, part-load behavior, fan and pump operation, controls and utility tariffs. Name each alternative clearly so the result can be traced to an actual design decision.

For an Indian project, verify the applicable electricity tariff, demand charges and operating calendar rather than relying on an unrelated regional default. Compare component consumption as well as the final cost. An apparently efficient cooling option may increase fan, pumping or reheat energy elsewhere.

Check comfort and unmet-load information alongside energy. A lower-consumption alternative that fails to maintain required conditions is not an equivalent service comparison. Present assumptions and the reason for any improvement with the totals, rather than treating the smallest number as an automatic recommendation.

This window separates ordinary energy summaries from a performance-rating analysis with defined proposed and baseline roles. Carrier's v6.2 example includes a LEED v4 reporting workflow.[14] Follow the methodology applicable to your project; selecting a report does not by itself establish that the baseline model meets its rules.

For a design study, write the comparison question before running alternatives. For example: how much does a change in fan control reduce annual electricity while delivering the same ventilation and comfort? Keep unrelated assumptions fixed. Review cooling, fan, pump and heating consumption separately to see whether a saving in one component creates an increase elsewhere.

Separate energy savings from tariff effects. Lower electricity use does not always produce the same percentage reduction in the bill when demand charges or time-dependent rates apply. Present the relevant units, annual totals and operating assumptions together. A reviewer should be able to explain why an option improves the design, not merely identify the smaller final number.

How to Read a HAP Report Without Selecting the Wrong Equipment

Start with the report identity and calculation basis

Read the project, alternative, system and zone names before reading the capacity. Confirm the input revision, software version, units and sizing basis. A valid result for the wrong system or an earlier drawing revision is still unsuitable for the current selection.

Also distinguish a design calculation from an annual simulation result. A monthly consumption total does not specify a peak coil capacity. A single design-day peak does not establish expected annual operating cost. Retain both outputs when the project requires both sizing and energy evaluation.

Air System Sizing Summary: coil duty is more than tonnage

Look for total and sensible coil duty, air conditions, associated airflow and peak time. Then inspect the fan sizing information separately. Carrier's sample explicitly distinguishes airflow at peak coil duty, maximum block airflow and the sum of individual zone peaks.[9] Those quantities answer different sizing questions and can occur at different times.

For a cooling coil selection, carry the airflow and entering/leaving air conditions forward with the required duty. For a chilled-water coil, also coordinate water temperatures and pressure-drop requirements. For DX or VRF equipment, check the manufacturer's performance corrections at the actual project conditions. A catalogue's headline capacity is not enough evidence.

Zone reports: check where the airflow goes

Review each zone's sensible and latent loads, required airflow, peak time and indoor design condition. Investigate outliers within genuinely comparable rooms: similar area alone does not make rooms thermally similar. An exposed meeting room can behave very differently from an internal circulation space.

Identify which requirement controls the design airflow. If ventilation sets a minimum above the sensible cooling requirement, the terminal and control sequence must handle that condition. If heating sets the larger duty, review winter operation rather than reducing the airflow just because it looks high on the cooling schedule.

Ventilation report: verify the minimum operating condition

Check the method and standard edition first. Follow the room population and area inputs through to the zone and system requirements. Pay particular attention to minimum primary airflow in variable-volume systems, since adequate outdoor-air delivery at peak cooling does not by itself demonstrate adequacy at reduced flow.

Do not confuse outdoor air with total supply air. Much of an AHU's supply may be recirculated. Similarly, air induced locally by a fan-powered terminal does not become outdoor air merely because it contributes to the discharge volume.

Psychrometric report: follow the air through the system

Trace outdoor air, return air, mixed air, coil leaving air and supply air where those points exist in the selected arrangement. Carrier's example presents temperatures, moisture properties and heat flows at system points.[11] Use the report to explain the process, not merely to collect another page for the submission.

For a coil removing moisture, expect a reduction in humidity ratio across the cooling process. Sensible reheat increases temperature without itself removing water vapor. Fan heat can raise the supply temperature downstream of the coil, depending on fan location. If the process seems inconsistent, revisit the selected arrangement and controls before assuming the report is wrong.

Energy reports: locate the reason behind the annual total

Separate cooling, heating, fans, pumps and other included uses when interpreting a comparison. Carrier's component energy-budget example illustrates this breakdown.[12] A reduction in compressor energy may be offset elsewhere, so review the whole modeled boundary.

Compare the operating service as well as the energy. The same occupied conditions, ventilation requirements and hours should be represented unless the comparison deliberately changes them. For an existing building, reconcile the model with meter periods, weather, occupancy and the equipment actually installed before making a savings claim.

Worked Example: From Room Load to Airflow and Coil Duty

Consider a hypothetical meeting room. These are teaching assumptions, not HAP-generated results or recommended ventilation rates. Suppose a checked room calculation gives 8.0 kW sensible cooling and 2.0 kW latent cooling at the hour being studied. The room is maintained at 24°C and receives air at 14°C.

Step A: separate sensible and total cooling

The 2.84 TR figure expresses the room total load in another unit. It does not mean a nominal 3 TR unit is automatically suitable. Available sensible capacity, latent capacity, airflow and design conditions still have to be matched.

Step B: estimate supply airflow from the sensible load

This check assumes air density 1.2 kg/m³ and specific heat 1.005 kJ/(kg·K). The 10 K difference is between room air and air delivered to the room. If supply air instead arrives at 16°C, that difference is 8 K and the required sensible airflow rises to approximately 0.829 m³/s, a 25% increase.

That change illustrates why a temperature assumption affects fan duty and duct sizing. It also shows why the coil leaving temperature should not casually be substituted for room supply temperature when downstream heat gains are significant.

Step C: identify the outdoor-air treatment duty

Assume the outdoor-air quantity has been established separately and corresponds to 0.10 kg/s of dry air. Suppose its enthalpy is 75 kJ/kg of dry air, while room return air is 50 kJ/kg of dry air. The incremental outdoor-air duty relative to return air is:

The enthalpy calculation includes sensible and latent effects together. Do not add a separate latent outdoor-air allowance on top of that same total. Also verify that enthalpy and mass flow use the same dry-air basis.

Step D: place that duty on the correct equipment

If the same coil handles the room load and untreated outdoor air, its simplified duty at this hour is approximately 10.0 + 2.5 = 12.5 kW before fan heat and other system effects. This is an illustrative energy balance, not a final HAP sizing result or a claim that both contributions peak together all year.

If a separate DOAS delivers ventilation air at room-neutral temperature and humidity, the DOAS carries that outdoor-air-to-room-condition duty. The room terminal still handles the room's own load. If the DOAS supply is colder or drier than room air, it may also offset part of the room demand. Model those actual delivery conditions rather than subtracting an arbitrary percentage from the FCU load.

Step E: connect duty to water flow, where applicable

For illustration, a 12.5 kW water coil with a 5 K water-temperature rise needs the following approximate mass flow, using water specific heat 4.186 kJ/(kg·K):

The volume conversion assumes density approximately 1,000 kg/m³. This establishes a thermal flow requirement only. Pipe size, pump head, valve selection and balancing still require the hydraulic calculations and actual fluid properties. Glycol mixtures require different properties.

Step F: keep annual electricity separate

Suppose an illustrative system delivers 50,000 kWh of annual cooling and has an effective cooling COP of 4.0 over that delivery. Cooling electricity would be approximately 12,500 kWh for the equipment boundary represented by that COP. Include fan, pump or auxiliary energy separately where it lies outside that boundary.

This is a conceptual check, not a substitute for hourly simulation. Real efficiency changes with load and conditions, and cost depends on the tariff. Do not use the 12.5 kW design-duty example as though the system continuously operated at that duty throughout the year.

Does HAP Replace Manual HVAC Calculations?

HAP automates detailed load and energy calculations, but engineers still need to establish the inputs, check the results and complete the rest of the design. Manual calculations are useful for checking individual quantities and understanding discrepancies. Repeating the entire hourly calculation by hand is rarely the best use of time.

Keep a short independent calculation sheet alongside the model. The examples below are simplified engineering checks, not outputs from the Carrier demonstration projects or universal design values.

Check 1: confirm load density and input units

Divide a room's reported cooling load by its floor area to obtain W/m², making clear whether the numerator is sensible or total room load. Compare rooms with similar use, exposure and operating conditions. A large difference is a reason to investigate; there is no single W/m² value that proves every office calculation is correct.

For a basic input check, 12 W/m² of lighting over 80 m² gives 960 W of installed lighting power. If the input schedule is 0.75 at a particular hour, the associated electrical input is 720 W. Compare that with the modeled input basis, allowing for any relevant fixture treatment. The instantaneous room cooling load can differ because radiant heat is stored and released later.

Check 2: reconcile the outdoor-air quantity

When the applicable ventilation method uses both people and floor area, the starting breathing-zone calculation is Vbz = Rp × Pz + Ra × Az. Here Rp is the per-person rate, Pz is design population, Ra is the per-area rate and Az is zone floor area.

For arithmetic practice only, assume 10 people, 2.5 L/s per person, 100 m² and 0.3 L/(s·m²). The result is 25 + 30 = 55 L/s. These assumed rates are not a recommendation for a particular occupancy or standard edition. Air-distribution effectiveness and system-level requirements may change the outdoor-air quantity ultimately required at the intake. Compare the same stage of the ventilation calculation when reviewing HAP.

Check 3: estimate sensible airflow

Use Qs = ρ × cp × V̇ × ΔT for a sensible air-side check. With air density approximated as 1.2 kg/m³ and specific heat as 1.005 kJ/(kg·K), the denominator is approximately 1.206 × ΔT when Qs is in kW and V̇ is in m³/s. Use density appropriate to the site for a more accurate check.

A 6 kW sensible load with a 10 K room-to-supply temperature difference requires approximately 0.50 m³/s, or 500 L/s. If the selected HAP report shows a materially different value, investigate its load basis, supply temperature, ventilation minimum and airflow constraints. Do not use total cooling load in this sensible-only equation.

Check 4: reconcile coil duty and fluid flow

For total air-side coil duty, compare entering and leaving air enthalpy using Q = ṁda × (hin − hout), with dry-air mass flow and matching enthalpy units. For chilled-water flow, use Q = ṁw × cp,w × ΔTw. The worked example above demonstrates the water-side calculation and why room load and coil duty can differ.

A water-flow check does not size the pipe. Pipe diameter also depends on the chosen velocity and pressure-loss criteria, available differential pressure, fittings, valves and the distribution arrangement. Likewise, HAP's supply airflow does not establish duct dimensions or the fan's required external static pressure.

What still needs a separate design calculation?

Complete duct pressure-loss calculations, fan duty checks, chilled-water network calculations, pump head, balancing requirements and manufacturer equipment selection using appropriate methods or tools. Develop diffuser layouts and check air distribution against the room arrangement. Electrical coordination and control sequences also need their own design work.

HAP may use fan, pump and system parameters within its analysis, but that is different from designing the installed distribution network. The final deliverable should connect the calculated thermal duty with equipment that can deliver it through the proposed ducts, pipes and controls.

Real-Life HAP Problems, Solutions and Final Checks

Before changing a suspicious result, identify the mechanism that could produce it. A very large perimeter load suggests checking exposure, glazing and shading. Similar loads in rooms with very different uses suggest checking copied inputs. Unexpected overnight energy suggests reviewing schedules and control operation.

• Check area, orientation and adjacency against the current drawings.
• Confirm sensible and latent gains are entered on the intended occupancy and equipment basis.
• Trace outdoor air through the actual system so it is neither omitted nor treated twice.
• Review safety factors and selection allowances together; avoid layering undocumented margins.
• Compare the selected equipment's available capacity at the design conditions, not just its nominal tonnage.
• Record the software version, input revision, unresolved assumptions and reports used for selection.

A useful submission includes the design basis, marked-up zoning plan, load and ventilation reports, equipment-sizing basis and a short review record. It should let another engineer reconstruct why the design was accepted without guessing what happened inside the model.

If airflow appears unusually high

First compare room and supply temperatures. A small sensible temperature difference needs more air for the same sensible duty. Next check minimum ventilation, heating requirements, any fixed airflow input and the zone grouping. Finally, confirm you are comparing the same airflow quantity and units in both reports.

If cooling capacity appears unusually low

Check unmodeled spaces, exposure, glazing, schedules and whether occupancy or equipment was omitted. Then trace ventilation and latent load to the correct system. Avoid applying an arbitrary multiplier before finding the cause; a missing outdoor-air path and an overly conservative safety factor require different corrections.

If the coil duty exceeds the room loads

Compare the same hour and the same sensible/total basis. Identify outdoor-air treatment, fan heat and other system contributions. A difference can be physically correct. The review question is whether each additional contribution can be explained, not whether two differently defined totals happen to match.

If two software versions give different results

Preserve the original project, rerun both with documented inputs and isolate a representative zone. Review changed defaults, converted data and the relevant release notes. If the discrepancy remains, prepare a small reproducible case with reports and assumptions for technical support rather than changing several unrelated inputs at once.

If an energy-saving option looks too good

Check whether operating hours, outdoor-air supply, indoor conditions or included energy uses changed inadvertently. Then inspect equipment performance data and the utility tariff. A model that simply provides less cooling, heating or ventilation is not demonstrating an equivalent-service efficiency improvement.

The manual spreadsheet and HAP do not agree

A typical situation is that a simple room spreadsheet gives one tonnage while HAP reports a higher coil duty. First identify whether both numbers represent the same room, system, hour and sensible/total basis. Check whether the spreadsheet includes outdoor-air moisture removal, fan heat and the same envelope and occupancy inputs.

Then compare components instead of only the grand total. Reconcile lighting power, people, glass area and outdoor airflow individually. A steady-state U × A × ΔT calculation does not reproduce the time-dependent response of sunlit construction, and adding each component's independent maximum can exaggerate a simultaneous peak. The solution is an explained difference, not forcing HAP to match a preferred spreadsheet value.

The BIM import fails, or the imported building looks wrong

Carrier's gbXML guidance identifies closed space volumes, associated surfaces and a compliant file as prerequisites for a usable import.[14] An architectural model that displays correctly can still be unsuitable for thermal analysis if space boundaries are incomplete.

Check the source model's levels, spaces, boundaries and openings before exporting again. Try a small representative portion in a separate test project to narrow down the issue. After import, compare floor areas and elevations with the drawings. Repair the source geometry where possible so the same defect does not return with the next architectural revision.

The program runs slowly on a detailed building

Distinguish a large calculation from a stalled application. Save the project, note the operation taking time, and identify whether the delay occurs during geometry processing, design sizing or annual simulation. For diagnosis, use a separate smaller case to isolate the affected geometry or system rather than repeatedly running the entire building.

Carrier's v6.2 release notes describe calculation-engine changes that can reduce run time for zones containing multiple spaces.[14] Check your installed version and relevant release notes. Remove accidental duplicate geometry and resolve validation errors. Do not merge thermally different zones solely for speed if doing so changes the control arrangement or design result.

The model shows unmet demand despite sufficient nominal capacity

A large capacity number is not proof that the system serves every zone at every hour. Examine when the problem occurs. Morning recovery after a temperature setback suggests a different investigation from persistent afternoon difficulty in a west-facing room.

Review thermostat and availability schedules, zone airflow limits, supply conditions, plant availability and actual equipment performance at those conditions. Carrier provides zone-temperature, hourly simulation and plant unmet-load reports to support this investigation.[1] Read each report's definition: a plant capacity shortfall is not the same measure as a zone temperature outside its control range. Correct the relevant input or design limitation, rerun and verify the affected hours.

The room reaches its temperature target but humidity is a concern

Check the moisture balance separately from the sensible load. Outdoor air, infiltration and people can contribute latent demand even when sensible cooling is modest. A room thermostat alone does not demonstrate that the proposed coil and controls can maintain the humidity criterion.

Trace the air process, review coil leaving-air conditions and compare the selected unit's sensible and total performance at the actual entering conditions. Examine part-load control and any required outdoor-air pretreatment or dehumidification strategy. Reheat, when justified by the design, adds energy and must be represented consistently. Simply adding nominal cooling capacity may leave the underlying moisture-control problem unresolved.

The selected unit's catalogue capacity does not match HAP

HAP establishes a required duty for the modeled conditions. A catalogue often presents capacity at a specified rating condition. Those conditions may differ from the project's outdoor temperature, entering-air state, water temperature or airflow.

Use the manufacturer's selection data at the actual duty point. Check both total and sensible capacity, air and water flow, pressure drops and operating limits. For a DX system, include applicable manufacturer corrections and system constraints. Keep the selection beside the HAP report so the reviewer can see how the calculated requirement becomes a specific equipment choice.

The energy estimate differs from the building's electricity bill

First align the accounting boundary. A whole-building bill can include lifts, tenant equipment and other uses that an HVAC-only model excludes. Then compare operating hours, occupancy, weather period, metered floor area and the tariff. A design-stage schedule is not necessarily how the building actually operates.

Use available meter trends, BMS records and an equipment inventory to replace uncertain assumptions. Compare monthly patterns before adjusting annual totals. Record calibration changes and their evidence; do not change efficiencies arbitrarily to make the bill match. A model calibrated to actual operation answers a different question from a peak design-load calculation.

The project cannot be opened, or results change after conversion

Confirm which HAP version created or last saved the file. Preserve the original before conversion and save the converted project separately. Recheck key inputs and rerun calculations; do not assume a report produced before conversion represents the current file.

If the issue persists, send technical support a reproducible description: software version, exact error text, steps leading to the problem and a suitably shareable example project. Carrier maintains software support and technical resources.[15] Review a project's confidential information before sharing it, and identify any simplification made to the support copy.

A useful sensitivity exercise before issuing the design

Save a baseline, then change one uncertain input at a time within a justified range. For example, test the approved glazing alternatives, the expected occupancy range or a proposed operating-hours change. Record the effect on zone duty, system airflow and energy separately.

Prioritize confirmation of the assumptions that materially alter equipment selection. Keep the accepted case identifiable and remove accidental test inputs before export. This turns uncertainty into a reviewable design decision instead of hiding it inside a blanket margin.

HAP vs. Other HVAC Design Software

Compare tools by the engineering decision you need to make. Load and energy analysis, detailed hydraulic design and coordinated construction drawings are distinct deliverables; a familiar software name alone does not establish suitability.

HAP vs Hysopt: a practical comparison

HAP combines building loads, system sizing and annual energy analysis. Hysopt emphasizes hydronic-system behavior, including pumps, valves, flows and control interactions. Its own comparison describes workflows where the tools are used together.[7]

For learning building loads and sizing reports, HAP is a relevant starting point. For a detailed investigation of how a water circuit and its controls interact, evaluate a hydraulic simulation workflow. Hysopt’s comparison is a vendor source, so assess its claims against your actual project requirements.

Learning HAP Software: Course Options

A useful HAP software tutorial should explain why an input changes the result. Changing occupancy, glazing or ventilation one item at a time is a better learning exercise than reproducing an unexplained final tonnage.

When choosing an Hourly Analysis Program training course, look for load-calculation fundamentals, psychrometry, a complete building exercise, report interpretation and reviewed assignments. Ask which HAP version is taught and how practice access works.

Carrier University offers HAP-specific instruction.[6] For a broader design path, Augmintech’s published HVAC syllabus includes manual and Excel load calculations, HAP input requirements and output analysis, alongside HVAC drafting. The goal should be a project you can explain: assumptions, inputs, sizing reports and design decisions.

Frequently Asked Questions

Sources and Further Reading

1. Carrier: Hourly Analysis Program. Product scope, sizing and energy-analysis capabilities.
2. Carrier: HAP v6 modeling and calculation methods. Graphical input, Heat Balance and EnergyPlus.
3. Carrier: HAP sample reports. Design, ventilation and energy reporting.
4. Carrier: eDesign trial request. Published trial duration and access process.
5. Carrier: official software downloads. Current and legacy installers; licence requirements.
6. Carrier University: load calculation using HAP v6. Training workflow and learning objectives.
7. Hysopt: HAP comparison. Vendor description of hydronic modeling and controls focus.
8. Carrier: HAP v6.4 New Features Guide, April 2026. Source of the eight software and export images reproduced for this explanatory walkthrough. Copyright Carrier 2026. Images retain their original interface content and source resolution.
9. Carrier: sample Air System Sizing Summary. Legacy output illustrating distinct coil, block and zone airflow quantities, not a v6.4 interface example.
10. Carrier: sample Ventilation Sizing Summary. Legacy example illustrating the calculation hierarchy; use the project's applicable standard edition and current software settings.
11. Carrier: sample System Psychrometrics report. Air-process quantities and report interpretation.
12. Carrier: sample Energy Budget by System Component. Component-level energy accounting. The worked examples in this article are separate illustrative calculations.
13. Carrier: HAP v6.0 New Features Guide, November 2022. Source of six foundational workflow screenshots, pp. 5–7 and 19. Copyright Carrier 2022. These are labeled v6.0, not v6.4.
14. Carrier: HAP v6.2 New Features Guide, April 2024. Source of the imported-model and energy-report-options screenshots, pp. 4 and 6. Copyright Carrier 2024.
15. Carrier: HVAC system design software support. Technical resources and support contacts. Use guidance appropriate to the installed version; some published technical notes concern legacy releases.