Energy Simulation of buildings is a practice of evaluating the energy use of a building through simulating and accounting for all the energy related issues and components. All buildings that have significant utility or energy use benefit from energy modeling. Not all energy efficient equipment or practices fit all situations. Analysis through energy calculations is a useful way to predict savings and calculate payback. Care should be taken to find the most worthwhile savings created in exchange for the typically higher up-front cost and effort.
Purpose
The goal of energy simulation of buildings is to accurately predict the energy use of a building to either test the energy performance of the building with regards to an established standard, or to compare and contrast two buildings in order to find the resulting energy savings.
Key Simulation Inputs and Assumption
A model is usually an attempt to simulate the energy operation of a yet un-built project. As such, many unknowns about that building must be estimated for the model. Literally hundreds of inputs will need to be entered to build a model. Some user-friendly programs have built-in industry standard defaults that speed up early model creation. The responsibility for the accuracy of these inputs resides with different team members. A typical set of modeling inputs might include the following.
-
Location
 |
| Climate Data |
-
Envelope
 |
 |
 |
| Architectural drawing | Construction envelope | Orientation |
 |
 |
 |
| U factor | G value | Transmittance |
 |
||
| Infiltration |
-
Internal Gains
 |
 |
 |
| Lighting | Equipments plug load | Sensible and latent (moisture) loads froom people |
-
Envelope
 |
 |
 |
| Heating System type,including the source,distribution and terminal units | Cooling system type,including the source,distribution and terminal units | Ventilation system types |
 |
 |
 |
| Fan and pump inputs | Heat recovery systems | Domestic hot water system |
 |
||
| Renewable energy systems |
Schedules:
- Lighting schedules;
- Equipment plug load schedules;
- HVAC system schedules;
- Ventilation schedules;and
- Occupancy schedules.
Stimulation Outputs:
Weather Variables:
- Dry-bulb temperature;
- Wet-bulb temperature;
- External dew-point temperature;
- Wind direction;
- Wind speed;
- Direct radiation;
- Diffuse radiation;
- Global radiation;
- Solar altitude;
- Solar azimuth;
- Irradiance;
- Cloud cover;
- Atmospheric pressure;
- External relative humidity;
- External moisture content;
Loads:
- Room heating plant sensible load
- Room humidification plant load
- System air heating load
- Auxiliary Vent heating load
- Boilers load
- Room cooling plant sensible load
- Room dehumidification. plant load
- System air sensible cooling load
- System air latent. Cooling. load
- Auxiliary ventilation sensible cooling load
- Auxiliary ventilation latent. Cooling. load
- Chillers load
- DHW heating demand
- DHW boiler load
- DHW solar input
- CHP heat generator
Energy Consumption:
- Boiler’s energy consumptionRoom humidification plant load
- Boiler’s Pump energy consumption
- Chiller’s Energy consumption
- Chiller’s Heat Rejection Pump energy consumption
- System’s Fans and Pumps energy consumption
- DWH & solar heating pump energy consumption
CO2 emissions produced by energy consumption:
- Boiler’s CO2 emissions
- Boiler’s Pump CO2 emissions
- Chiller’s Energy consumption
- Chiller’s Heat Rejection Pump CO2 emissions
- System’s Fans and Pumps CO2 emissions
- DWH & solar heating pump CO2 emissions
Room Variables:
- Air temperature
- Dry resultant temperature
- Environmental temperature
- Mean radiant temperature
- Dew-point temperature
- People dissatisfied
- Predicted mean vote
- Comfort index
- Relative humidity
- Moisture content
- Room CO2 concentration
- Space conditioning sensible
- Steady state heating plant load
- Internal gain
- Solar gain
- External conduction gain
- Internal conduction gain
- Conduction gain
- Air system input sensible
- Aux vent gain
- Natural vent gain
- Infiltration gain
- External ventilation gain
- Internal ventilation gain
- System air supply
- Natural vent
- Space conditioning
- Humidification plant load
- Dehumidification plant load
- Cooling + dehum plant load
- Equipment latent gain
- People latent gainNumber of people
- DHW heating demand
- Air system input
- Ventilation/infiltration. latent gain
- Convective room plant load
- Convective lighting gain
- Convective equipment gain
- Convective people gain