Standards
Compliance with
ASHRAE Standard 183
ANSI/ASHRAE/ACCA Standard 183 sets the minimum requirements for peak cooling and heating load calculations in every building except low-rise residential. Below is each requirement in sections 5 through 10, and how HVAKR meets it. All 29, nothing skipped.
- Cooling load method
- ASHRAE Radiant Time Series (RTS)
- Design day coverage
- 288 calculations — 24 hours × 12 months
- Weather data
- ASHRAE climatic design conditions by latitude and longitude
- Requirements addressed
- All 29, sections 5 through 10
5Weather Data and Indoor Design Conditions
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 5.1Indoor design conditions shall be established by owner criteria, local codes, or comfort criteria. | HVAKR allows users to specify indoor setpoints, including dry-bulb temperature for summer and winter and relative humidity. |
| 5.2Cooling calculations shall use values of outdoor air temperature and humidity for the building use, the building location, time of year, and time of day. | Calculations use hourly profiles for outdoor air dry-bulb and wet-bulb temperature for one design day per month, based on climatic data local to the building. |
| 5.3Solar radiation for cooling calculations shall use solar flux conditions for the building location, time of year, time of day, and orientation of the surface receiving the solar radiation. | Calculations use hourly profiles for solar flux for one design day per month, based on the latitude, longitude, and surface orientation of the building. |
| 5.4Heating calculations shall use values of outdoor air temperature for the building use and the building location. | Calculations use winter design outdoor air temperature and humidity, based on climatic data local to the building. |
6Cooling Load Method
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 6.1The calculation method shall account for convective heat gain, radiant heat gain, and the thermal mass effect on cooling load. | HVAKR uses the ASHRAE Radiant Time Series (RTS) method, which accounts for convective and radiant heat transfer and for the delay in heat transfer influenced by the thermal properties of the building and its components. |
| 6.2The cooling load calculation shall address the hours of the day and months of the year necessary to establish the peak cooling load and the hour at which it occurs. The peak load may occur at any of a number of possible hours. | HVAKR computes the cooling load for all 24 hours of one design day per month, giving 288 calculations. These are sifted to identify the peak load and its hour for each space, zone, and system. |
7External Heat Gains
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 7.1.1Fenestration. The calculation method shall account for both temperature-driven heat gain and solar heat gain. | Window load calculations include both the convective (temperature-driven) and radiant (solar-driven) heat gain for the assembly. |
| 7.1.2The temperature-driven heat gain shall be calculated using the thermal performance of the entire fenestration assembly. | Calculations use the user-specified overall U-value for the assembly to determine the temperature-driven heat gain. |
| 7.1.3The solar heat gain shall be calculated from incident solar flux and the solar performance of the entire fenestration assembly. | Calculations use the solar flux hitting the assembly and the user-specified solar heat gain coefficient (SHGC) of the assembly to determine window solar heat gain. |
| 7.1.4The solar heat gain calculation shall account for interior shading from devices such as blinds, shades, or drapes when such devices are present. | HVAKR allows the user to specify interior shading properties for windows, and accounts for interior shading when computing solar heat gain if those properties are present. |
| 7.1.5The solar heat gain calculation shall account for exterior shading when present. | HVAKR allows the user to specify horizontal and vertical exterior shading — top overhang and side overhang depth and offset — and accounts for exterior shading when computing solar heat gain if those properties are present. |
| 7.2Opaque Building Envelope. The heat gain of opaque building envelope components shall account for solar radiation and temperature-driven heat gain, shall consider the thermal performance of materials in the opaque building envelope component, and shall consider the time delay occurring as heat is conducted through the material layers. | Calculations include heat gain from solar radiation hitting the envelope component and heat gain or loss from the temperature difference between exterior and interior. HVAKR allows the user to specify the assembly type, overall U-value, and absorption coefficient of each component. The RTS method accounts for the delay in heat transfer influenced by the thermal properties of the assembly. |
| 7.3Infiltration. The calculation method shall account for separate sensible and latent infiltration heat gains when infiltration exists. | HVAKR allows the user to specify infiltration airflow and calculates both sensible and latent infiltration heat gains when infiltration airflow is present. |
8Internal Heat Gains
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 8.1Internal heat gains shall be included in the cooling load. | Calculations include internal heat gains. |
| 8.2Sensible and latent heat gain components of all internal gain contributors shall be considered separately. | HVAKR calculates each individual source of internal heat gain, and considers sensible and latent heat gain separately for sources that produce both. |
| 8.3Evaluation of heat gains from the occupants shall take into account the number of occupants, their activity levels, and the occupancy schedule. | HVAKR allows the user to specify the number of occupants, the per-person sensible and latent heat gain, and the hourly schedule for each space type. These inputs give the heat gain from occupants for each hour in the space. |
| 8.4Evaluation of heat gains from lighting and internal equipment shall consider their operation schedules and load factors. | HVAKR allows the user to specify the load factor and hourly schedule for lighting and equipment for each space type. These inputs give the heat gain from lighting and equipment for each hour in the space. |
| 8.5Evaluation of heat gains from lighting equipment shall account for heat transfer to the ceiling plenum (if applicable). | HVAKR allows the user to specify the percentage of lighting load applied to the ceiling. When ceiling plenum heat gain is specified, HVAKR applies that gain to the system load and omits it from the space and zone loads, and reports peak loads both with and without the plenum. |
9Heating Load
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 9.1Heating load calculations shall be based on peak temperature-driven heat loss through the building envelope. | Calculations use peak temperature-driven heat loss at winter design conditions to determine heating loads. |
| 9.2Credit for solar heat gains and for internal heat gains shall not be included as part of the calculation of the peak heating load. | Calculations include neither solar heat gains nor internal heat gains when determining heating loads. |
| 9.3Infiltration shall be accounted for when it exists. | HVAKR allows the user to specify infiltration airflow, including a separate winter infiltration requirement, and calculates both sensible and latent infiltration heat gains when infiltration airflow is present. |
| 9.4Heating load calculations shall account for cold processes or equipment in the zone that absorbs heat (for example, some refrigerated cases). | HVAKR allows the user to specify miscellaneous heating loads for each space. A specified miscellaneous heating load is included in the heating load calculation. |
10System Cooling and Heating Loads
| ASHRAE Standard 183 requirement | How HVAKR complies |
|---|---|
| 10.1Cooling and heating system loads shall account for the capacity required to accomplish psychrometric processes. Psychrometric processes include conditioning for reheat, dehumidification, and air mixing. | HVAKR runs the psychrometric processes for each system when calculating system capacity requirements and coil sizing, based on the system configuration specified by the user. |
| 10.2Energy from fans and pumps used in cooling systems shall be accounted for in system cooling loads. | HVAKR allows the user to specify fan heat gain and other system inefficiencies — as a power input or a temperature rise — when configuring each system. Fan heat gain and other inefficiencies are applied to the system loads when present. |
| 10.3Heat transfer through piping and ductwork walls shall be accounted for in determining system loads. | HVAKR allows the user to specify duct heat gain and loss when configuring each system. Duct heat gain and loss is applied to the system loads when present. |
| 10.4Duct leakage shall be considered in determining system load. | HVAKR allows the user to specify duct leakage when configuring each system. The additional load from duct leakage is applied to the system loads when present. |
| 10.5Outside air cooling and heating loads shall be calculated for the particular system configuration and weather data. | HVAKR includes outside air ventilation loads when calculating cooling and heating loads for each system, based on the system configuration specified by the user and climatic data local to the building. |
| 10.6Diversity due to variations in actual occupancy, lighting, or equipment use shall be considered in determining system cooling loads. | HVAKR allows the user to specify separate occupancy, lighting, and equipment diversity factors when configuring each system. Diversity is applied to the system loads when present. |
| 10.7Based on the specific type of system designed, the system cooling and heating loads shall account for inherent system inefficiencies such as damper leakage. | HVAKR allows the user to specify other system inefficiencies when configuring each system. The specified inefficiency can cover damper leakage, coil bypass, or any other inherent system inefficiency, and the additional load is applied to the system loads when present. |
About this statement
What This Is, And What It Is Not
This is a compliance statement: the software vendor documents each requirement of Standard 183 and how the program meets it. It is the same form of document Carrier, Trane, and other load-calculation vendors publish for their own tools. ASHRAE does not certify or stamp load-calculation software, so no vendor — including us — holds an ASHRAE certificate for it. Read these, check them against your own project, and hold us to them.
Standard 183 also states that an accurate load depends on the inputs as much as the method. HVAKR reports every load component, design condition, and assumption so a reviewer can verify both.
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