VisualDOE FAQ
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Contents
INSTALLATION (click to see questions)
PROJECT (click to see questions)
BLOCKS (click to see questions)
FACADES (click to see questions)
SYSTEMS (click to see questions)
PLANT (click to see questions)
ORGANIZERS AND EDITORS (click to see questions)
3D VIEWER (click to see questions)
RUNNING SIMULATIONS (click to see questions)
GENERAL (click to see questions)
GLOSSARY OF TERMS
Glossary of Terms
- A control on the outside air damper that can increase the volume of outside air when increasing outside air can save energy. The control can be based on drybulb temperature, enthalpy, or both temperature and enthalpy.
- The outdoor and/or indoor temperature and humidity conditions that are used to calculate EER and other energy efficiency ratings based on ARI (American Refrigeration Institute) standards.
- Building azimuth is specified by giving the azimuth of the front of the building. The azimuth is the angle between a line that projects perpendicular to the building facade and true north as measured in a clockwise orientation. If you use a compass to determine north, be sure to correct for the magnetic deviation. The following figures are examples to illustrate the azimuth of the front of the building.
- Block, as used by VisualDOE
- A group of thermal zones used by VisualDOE. Standard blocks are rectangular, L-shaped, U-shaped, T-shaped, H-shaped, etc. A block can consist of one or more floors. Standard blocks can have one of three different zoning patterns. If floors have the same shape, but different zoning arrangements, you can create additional blocks and assign a different type of zoning to each block. When a block overlaps a block beneath it, VisualDOE creates a floor. When a block sets back from the one beneath it, a roof surface is created for the lower block. You do not need to worry about these details, VisualDOE takes care of them. You can think of a block as an object that can be rotated, stretched, pushed and otherwise manipulated. You can also create custom blocks.
- Ceiling Bypass VAV System
- A multi-zone system with a constant volume fan at the air handler. The air handler receives chilled water from a central plant. This system reduces the supply of air to the zone by diverting air into the plenum space, where it is returned to the fan. A plenum return is assumed for this system.
- A multi-zone system served by a central plant. The system is similar to the variable air volume system with the addition of induction mixing boxes to provide individual temperature control for one or more zones. Induction flow is limited to a maximum of 50% of the supply air so reheat coils are often installed to provide additional temperature control.
- A type of on-hours control of the supply fan. The fan operates at a constant speed and delivers a constant volume of air.
- Constant Volume Reheat Fan System
- A multi-zone, constant volume system served by chilled water from a central plant. Control to each of the zones served by the system is maintained by reheating the air at the zone as necessary. Supply air is typically delivered at a temperature cold enough to satisfy the cooling requirement of the warmest zone. Supply air in all the other zones is reheated.
- The zone used for primary control of an HVAC system. This zone is selected for each system by holding down the control key and clicking on the zone you want to be the control zone. You may only select one control zone If you assign more than one zone to single-zone systems, the system will attempt to meet the needs of the control zone only.A type of off-hours control of the supply fan. If the temperature in any zone falls below the throttling range specified for that zone, the system supply fan will come on to satisfy the load. Typically, the temperature setpoints during off-hours will be higher for cooling and lower for heating.
- A type of off-hours control of the supply fan. If the temperature of the control zone falls below the throttling range, the system supply fan will come on to satisfy the load. Typically the temperature setpoints during off-hours will be higher for cooling and lower for heating.
- A type of off-hours control of the supply fan. This off-hours fan control method is only available for zones that are served by power induction units. Only the fan in the power induction unit would come on and not the main system supply fan. This method will typically only be capable of satisfying off-hours heating loads, since power induction units typically have heating coils but not cooling coils.
- A type of on-hours control of the supply fan. This type of control is typical of water source heat pump systems and residential systems, but the control type is available for other systems as well. When there is no heating or cooling load, the fans are off. If this option is chosen, you should recognize that no outside air will be provided to the space while there are no heating or cooling loads. Outside air ventilation should be provided by natural ventilation or other methods.
- Daylighting may be specified for any of the perimeter zones. When daylighting is modeled, the ceiling is assumed to have a reflectance of 80%, walls 60% and floors 20%.If interior shade is specified, windows are assumed to have a medium colored venetian blind that is closed when solar gain exceeds 30 Btu/h-ft������².When the blind is closed, the visible light transmission of the glazing is assumed to be reduced to 60% of the light transmission of the window with the blind open. The reference point for daylighting calculations is assumed to be located in the center of the daylit zone.
- The illumination level in footcandles that the electric lighting system tries to maintain. A photocell in the zone measures the illumination level at a reference position 7.5 ft from the window. When it drops below the design illumination, the electric lights are turned on or brightened. When the illumination level is greater than the design illumination, the electric lights are dimmed or turned off.
- A mechanism that recovers heat from the superheated gas of a direct expansion air conditioner. The heat may be used for space heating or space heating in combination with water heating.
- A type of on-hours control of the supply fan. The fan operates at a constant speed, and air flow is controlled by opening and/or closing dampers located at the fan discharge. This is equivalent to "riding the fan curve". This type of control is appropriate only for variable air volume systems.
- With heating degree day and bin methods of calculating annual energy use, internal loads such as lighting, occupants, equipment, etc. are multiplied times a diversity factor to consider the fact that the peak condition does not exist for all hours. Diversity factors are not used however with hourly simulation programs such as DOE-2.Diversity is included in the schedule of operation.
- The temperature one reads on the a “normal thermometer” in degrees Fahrenheit (������°F)- usually referred to as DBT.
- A multi-zone system with two coils at the fan, commonly referred to as a hot deck and a cold deck. both hot and cold air is delivered to a mixing box located in each zone. The mixing box then mixes the hot air and the cold air supply to deliver a constant volume, but variable temperature flow of air to the zone. Thermodynamically, this system is similar to the multi-zone system; the difference is that the mixing takes place at the zone rather than at the air handler.
- The power in walls of all equipment (other than lighting) in a zone divided by the floor area of the zone. Do not consider diversity of load since the value you enter is modified for each hour by the equipment schedule.
- Evaporative Cooling System
- A single-zone system with indirect and/or indirect evaporative cooling. Several heating sources are available including hot water from a central plant, a gas furnace, an electric heat pump (reverse cycle) or electric resistance.
- An architectural term for the side of a building. VisualDOE uses this term to refer to a particular floor and a side.
- The VisualDOE library includes constructions, climates, fenestrations, utility rates and other data when it is distributed. Most of these records are fixed. This means that you can add additional records, but you may not delete or modify fixed records.
- Floor Panel Heating System
- A system that provides heating to one or more zones by circulation of water through pipes embedded in the floor or the ceiling. This system has no fan and provides no outside air.
- Four-Pipe Fan Coil System
- A single-zone system that is served by chilled water or hot water from a central plant. Because of the four-pipe configuration, some systems can be in a heating mode, while others are in a cooling mode. Typical applications are hotel rooms or residential buildings.
- Four-Pipe Induction Unit System
- A multi-zone system that is a mixed hydronic and air system. The system is capable of providing simultaneous heating or cooling to a number of individually controlled zones. A central fan provides a constant flow of primary air to the zones. This air is generally supplied at a high velocity to induce additional air from the zone. A coil in the induction unit can operate in either a heating or cooling mode (four-pipe).
- The decimal fraction of lights in the zone that are under the influence of the daylighting controller. For instance, a space might have some decorative lighting included in the specified lighting power density that is not turned off or dimmed in response to available daylight. If such lighting represented 1/3 of the lighting power in the zone, a value of 0.67 would be entered for the fraction of lights controlled. The fraction of lights controlled needs to be specified only when a zone is modeled with daylighting.
- Heating and Ventilation System
- A constant volume, single-zone system without cooling capability or humidity control. In its most basic configuration, the system provides forced air heating from an air handling unit that contains a heating coil, filters and a supply fan. Several heating sources are available including hot water from a central plant, a gas furnace, an electric heat pump (reverse cycle) or electric resistance.
- A type of on-hours control of a centrifugal supply fan. The fan operates at a constant speed. Air flow is controlled by vanes located at the inlet to the drum of the fan. This type of control is appropriate only for variable air volume systems.
- The peak lighting power in a space in watts divided by the floor area of the space. The lighting power should include the ballast and any other parasitic loads. Do not consider diversity of use when specifying the lighting power density. Diversity is handled on an hourly basis by the lighting schedule.
- The ratio of the minimum volume of supply air to the maximum possible volume of supply air. This is specified for zones that are served by variable air volume systems, packaged systems or power induction units.
- A multi-zone system with both a heating coil and a cooling coil at the central air handler. The air handler receives chilled water or hot water from a central plant. A separate duct leaves the air handler to serve each thermal zone. Air from the hot deck and the cold deck is mixed at the central air handler to provide the necessary temperature to satisfy the need of each zone. Thermodynamically, this system is similar to the dual duct system; the difference is that the mixing takes place at the air handler rather than at the zone.
- The maximum number of people in a space, specified as ft���² per person. The value you enter will be modified for each hour by the people schedule.
- Packaged Gas Solid Desiccant System
- A small packaged unit that uses a desiccant while in conjunction with direct and indirect evaporative cooling, instead of the usual DX coils. The unit uses a gas fired hydronic heater to regenerate the desiccant and to provide space heating. The result is a unit that primarily consumes gas to provide heating and cooling. [Not implemented in VisualDOE.]
- Packaged Multi-Zone Fan System
- A multi-zone system with both a heating coil and a cooling coil at the central air handler. Cooling is provided by a direct expansion air conditioner that is part of the packaged equipment. A separate duct leaves the air handler to serve each thermal zone. Air from the hot deck and the cold deck is mixed at the central air handler to provide the necessary temperature to satisfy the need of each zone. Several heating sources are available including hot water from a central plant, a gas furnace, an electric heat pump (reverse cycle) or electric resistance.
- Packaged Single-Zone System
- A single-zone packaged air conditioner. Several heating sources can be used including a heat pump, which means that the air conditioner works in reverse to provide heating to the zone. Other heating sources are electric resistance, hot water from a central plant or a gas furnace. This is the most common of all equipment for commercial buildings.
- Packaged Terminal Air Conditioner System
- A single-zone system capable of providing either heating or cooling to a room or space. Units are typically installed in a window or in an opening in the wall (through-the-wall). Cooling is provided by a direct expansion air conditioner with an air-cooled condenser. A variety of heating sources are available. Typical applications are hotel/motel guest rooms, hospitals, nursing homes, and office buildings. All PTAC units discharge air directly into the room with no ductwork.
- Packaged Vari.-Volume, Vari.-Temp. System
- A multi-zone variable volume, variable temperature system. It behaves like a packaged single-zone system when no heating or cooling is required by the control zone so mixed air is delivered to the zone for ventilation. In this mode, the heating and cooling capacity is cycled off. It also behaves like a VAV system in that it adjusts the airflow to the zones to match the heating and/or cooling requirements of the control zone.
- Packaged Variable Air Volume System
- A multi-zone system where the primary means of controlling zone temperatures is to vary the volume of air delivered to a zone. Cooling is provided by a direct expansion air conditioner that is part of the packaged equipment. Each thermal zone has a variable air volume box that is capable of modulating the volume of air between 100% and some minimum amount, usually about 30% of the maximum. VAV boxes can also have reheat capability, especially for perimeter zones. If the zone is still cold after the supply of air has been reduced to the minimum, then the air is reheated as necessary to maintain the setpoint temperature. Several heating sources are available including hot water from a central plant, a gas furnace, an electric heat pump (reverse cycle) or electric resistance.
- The space between the ceiling of one floor and the surface of the floor above. HVAC ducts, VAV boxes, pipes, lighting fixtures and other building equipment is generally located in the plenum space. HVAC systems with air distribution can use the plenum for returning air to the fan system.
- Powered Induction Unit System
- A multi-zone system similar to a variable air volume system. Chilled water is provided to the air handler from a central plant. The main difference between a PIU system and a standard VAV system is that each VAV box has a small fan that can draw air from the plenum space in order to maintain a more constant flow of air into the zone. VisualDOE can model two common zone fan arrangements: a series terminal unit and a parallel terminal unit. These are specified by selecting Systems|Zones.
- If the system has a preheat coil, you enter the heating source by making a selection from a drop down list box and enter the preheat temperature. Possible heating sources include hot water from a central plant, furnace, or electric resistance.
- A constant volume, single-zone system typical of those used in single family homes. Unlike most of the other systems, the residential system is not capable of providing outside air. Cooling is provided by a direct expansion air conditioner. Several heating sources are available including hot water from a central plant, a gas furnace, an electric heat pump (reverse cycle) or electric resistance.
- Residential Variable-Volume, Variable-Temperature System
- A multi-zone residential style system featuring multiple, individually ducted and thermostatically controlled zones. Central heating and cooling are available from a high efficiency variable speed heat pump. Each thermostat controls a motor driven air damper in the zone duct. These dampers can close completely, giving zero airflow to the zone. Thus, some zones can be conditioned, while others are permitted to float. The system can also do simultaneous heating and cooling in that it can switch between cooling one group of zones and heating another group of zones within the one-hour time step of DOE-2 simulations.
- A type of off-hours control of the supply fan. If this option is selected the fans will not come on during off hours even if there are heating and/or cooling loads.
- A thermal zone is a space within a building that has its own temperature control. For buildings served by variable air volume (VAV) systems, a thermal zone is equal to the area served by each VAV box. In general, a separate thermostat means a separate thermal zone. In modeling buildings, it is common practice to group thermal zones that have the same solar exposure or similar loads.
- A single-zone system that is served by chilled water or hot water from a central plant. Because of the two-pipe configuration, all systems must be in either a heating or cooling mode. Typical applications are hotel rooms or residential buildings.
- Two-Pipe Induction Unit System
- A multi-zone system that is a mixed hydronic and air system. The system is capable of providing heating or cooling to a number of individually controlled zones. Since the hydronic component of the system is in either a heating or cooling mode (two-pipe), all induction units must be in either a heating or cooling mode. A central fan provides a constant flow of primary air to the zones.
- A type of on-hours control of the supply fan. Two-speed fan control is typical for packaged terminal air conditioners but is available for other systems as well. If this option is selected, then additional information must be entered on the air volume, efficiency, heating capacity, and cooling capacity at the low speed.
- A single-zone heater, usually suspended in the space. Several heating sources are available including hot water from a central plant, a gas furnace, or electric resistance.
- A single-zone heater, usually suspended in the space. The system is similar to the unit heater, except that it can provide a supply of outside air. Several heating sources are available including hot water from a central plant, a gas furnace, or electric resistance.
- Variable Air Volume System
- A multi-zone system where the primary means of controlling zone temperatures is to vary the volume of air delivered to the zone. Chilled water is provided to the air handler from a central plant. Each thermal zone has a variable air volume box that is capable of modulating the volume of air between 100% and some minimum amount, usually about 30% of the maximum. VAV boxes can also have reheat capability, especially for perimeter zones. If the zone is still cold after the supply of air has been reduced to the minimum, then the reheated air is necessary to maintain the setpoint temperature.
- Single Zone Variable Temperature System
- This system has both a heating coil and a cooling coil at the main air handler that delivers air at a temperature necessary to satisfy the central zone. This system typically serves just one zone. If other zones are served by the system, heating and cooling coils are used at the zone level to heat or cool the air as necessary to serve the needs of the additional zone.
- A type of on-hours control of the supply fan. The speed of the fan is controlled with a variable frequency drive or other means to maintain the required air volume. This type of control is appropriate for variable air volume systems.
- Water Loop Heat Pump System
- A single-zone system (also known as a California heat pump or a hydronic heat pump). A condenser water loop provides a source for heat rejection or absorption.
- A temperature reading, in ���°F, which takes into account the amount of moisture in the air. Its value can be obtained by spinning a thermometer with a wet wick encasing the bulb through the air (known as sling psychrometer). If the air is dry it will absorb moisture from the wick and indicate a low wet bulb temperature. Conversely, if the air is humid little moisture will evaporate from the wick and a high wet bulb temperature will be indicated.
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