ESP-r Source Distribution

The ESP-r source is partitioned into a number of folders as follows:
 
 
 
Folder name Contents
bin Scripts used in setting up esp-r and managing simulations. The script esp-r-dir will create the initial folders for the esp-r executables, databases and exemplar models. 
cetc Source code providing additional BASESIMP coefficient sets. Contributed by NRCan, Ottawa
climate Climate sets distributed with esp-r.  Mostly IWEC files downloaded and converted from USDoE simulation tools directory. Also holds climatelist file which holds the location and documentation on climate files used by esp-r.
databases ASCII versions of the databases distributed with esp-r. The Install script converts these into binary databases as required.
defaults Holds the file default which contains a list of the default models and databases which will be offered to the user.
env Holds examples of `dot` files which can be placed in users home folders to define environment variables, configure window managers and provide a background image.
esruaco Code related to accoustic calculations  Source code (aco.F) .
esrub2e Code supporting direct links between building energy management systems and the esp-r simulator.  Source code (b2e.F) 
esrubld Core code of the building simulator (solvers and subsystems)
esrubps The integrated simulator (uses code from esrubld, esrumfs, esruplt etc.)  Source code (bps.F) 
esruc2e Code supporting the calculation of wind pressures on specific portions of a building facade based on the CPCALC method. 
esrucfg Code of the surface topology checking module.  Source code (cfg.F) 
esruclm Code of the climate display and analysis module.  Source code (clm.F) 
esrucnv Code of the model conversion modules (various combinations of esp-r, dxf, thf, tsbi3) as well as vector image conversions (xfig, viewer)  Source code (ecnv.F) 
esrucom Common code imported by other modules (everything from I/O facilties for simulation model files (source files:  model configuration   casual gain controls   zone construction files   zone controls   zone geometry   zone operations  ) and databases (source files:  materials constructions opticscommand line parsing  and  psychrometrics .
esructl Code realted to global control functions. 
esrudfs Code supporting CFD calculations.  Source code (dfs.F) 
esrue2r Code of the visual assessment tool (wrapper around Radiance).  Source code (e2r.F) 
esrueco Code supporting life cycle cost and environmental impact assessments.  Source code (eco.F) 
esrugrd Code of the 2-3D conduction gridding module.  Source code (grd.F) 
esruish Code of the shading and insolation calculation module.  Source code (ish.F) 
esrumfs Code supporting calculation of mass flow networks.  Source code of the stand-alone solver (mfs.F) 
esrumld Code supporting micotoxin growth calculations and database of growth curves.  Source code (mld.F) 
esrunet Code of the graphic (flow) network creation module.  Source code (network.F) 
In order to appreciate how design problems may be modelled, it is useful to consult a range of examples. To this end ESP-r incorporates preconstructed models of incremental complexity that may be loaded, examined and simulated. Some of the simpler models are presented here. Several modelling case studies are also available which illustrate the application of modellng and simulation to real buildings.

Single zone problem

For training purposes it is useful to begin with a minimal problem description and then progressively add features and complexity to more closely represent the observed reality. The following image shows a wireframe view of a single thermal zone with a list of its surfaces and attributes. Such a model is used to help users appreciate the underlying model data.
Composition of a single zone model.

one zone model



An office portion

The intention of this 3 zone model is to allow users to explore how simple models may be extended over time to address specific issues as they arise. The following image shows the model before and after the addition of shading obstructions.
Composition of multiple zone model with and without shading.

adding shading obstructions




The ESP-r training directory includes the above model /usr/esru/esp-r/training/3z_bld) with several variant configurations located within the cfg subdirectory follows.

building_basic, the basic three zone model
building_bls, with blind shutter control
building_shd, with shading
building_shd_vwf, as building_shd with explicity view factors
building_mass_a, a basic building with infiltration air flow
building_mass_b, with infiltration and pening doors
building_mass_c, with infiltration and opening windows
The constructions for each models are defined in the file building.mlc while alternative control definitions are located in the cfg directory as files
building.ctl, reception and office heating system control
pre-heat.ctl, all zone heating with pre-heat period
temp-match.ctl, match temperature of other zones to that prevailing in the reception
building_mass_b.ctl, heat reception only
building_w.ctl, as building.ctl but with window control
building_s.ctl, window control only, no heating
The following is a synopsis of each variant.building_basic
Three zone building with ideal control, scheduled air flow (default treatments). Purpose is to look at the added topology definitions required of a multi-zone problem. Building_basic makes use of most of the basic descriptive files.
building_bls
In the case of building_bls blind shutter control has been added to the office. To access this supply the name building_bls for the problem name and the relevant information will be loaded. Note that building_bls now references office.utl which in turn references office.bls.
building_shd
This is the basic building with addional details of obstructions and the inclusion of a shading database for the reception. Shading has been calculated for the reception (surfaces south west glz_s door_w) for the period January - December. Note that file building_shd now references reception_shd.utl rather than reception.utl.
building_shd_vwf
In the case of building_shd_vwf the model was made more robust by upgrading the default area weighted viewfactors between surfaces in the reception with viewfactors calculated by a ray-tracing method. The actual calculations are performed by the shapefactor program. Note that the problem file building_shd_vwf now references reception_shd_vwf.utl.
building_mass_a
The basic building with air movement restricted to flows via crack openings (under doors and around windows) in the occupied spaces. Separately, the roof is vented by soffit and ridge vents. Use the configuration control file building.ctl_w which provides 1kW to the reception and office.
building_mass_b
A variation in base case with the addition of a component `door' between the rooms in the mass flow network. Use the configuration control (ctl/building_mass_b.ctl) which supplies 2kW heat to the reception but nothing to the office. During simulation notice how the air movement between the rooms provides much of the heating to the office.
building_mass_c
This variation add control of window openings to the previous network. If you are running a summer simulation use building_s.ctl, if a winter simulation use building_w.ctl.

Air flow networks

The base case air flow network is described in building.mfn_a and contains four boundary nodes (north, east, south, west) and three nodes (roof, recep, offic) which match the thermal zones. Air flow components (drcrk, wincrk, soffit, roofv) define the flow restrictions. The flow paths are between each zone and the outside via window cracks and between the two occupied rooms via a crack under the door. The roof space has two flow paths to the outside - one through the soffit and one by way of the roof vent.

The air flow network with window control is building.mfn_c. The control is made via a configuration control file. A window in the reception is assumed to open if the room temperature rises above 20°C. A similar set of paths is defined for the office.

During a summer simulation see how flow is restricted to the cracks in the windows until the room warms and then the window opens, flow is allowed and then when the temperature drops below 20°C the window closes. In the results analysis you will probably detect a sawtooth pattern as the windows open and close. The decision to open or close the cracks in the windows until the room warms and then the window opens, flow is allowed and then when the temperature drops below 20°C the window closes. In the results analysis you will probably detect a sawtooth pattern as the windows open and close. The decision to open or close the window is only taken once per timestep and you should experiment with different simulation timesteps to see how this ventilation control changes.

Supplementary control files

Two other configuration control files are provided for this 3-zone problem.
(1) pre-heat.ctl
This file provides for a typical daily 3-period control schedule.

Control schedule for all three zones:
00.00 - 09.00 preheat
09.00 - 18.00 ideal control
18.00 - 24.00 free-float

(2) temp_match.ctl
This file provides for a temperature matching control strategy whereby a zone's air temperature is controlled to follow that of another zone (the reception in this case).

Control schedule for office and roof:
00.00 - 24.00 match Zone_1 air temperature.

House with conservatory for solar ventilation preheat

Simulation can be used to explore the potential for novel energy conservation approaches. In this case the example model deals with a two level detached domestic dwelling with a conservatory used to preheat the ventiliation air.
    Hidden line view of house model.
wireframe of house



Office natural ventilation

Simulation the model was used to explore alternative environmental control strategies for office buildings. The model was established to support a natural ventilation study.
The speculative office block model.
aberdeen office
 
 

Model details.

aberdeen exploded
The air flow network.

air flow network




AHU plant and control system

This example demonstrates the simulation of a combined building and plant model. This plant model corresponds to a packaged air handling unit.
Plant network model.

ahu plant


Building Model:
The building model is described by three zones, each representing a distinct conditioned area. The zones are 1-reception, 2-officea and 3-roofspace.
Plant Network:
The plant network augments the building model and consists of 14 components describing the air handling unit:
The pre- and re-heat coils are standard flux control heating coils taken from the ESP-r plant component database, the maximum output of each coil is 3.5kW. The cooling coil is also a standard flux control model with a maximum capacity of 1kW. If a greater level of granularity is required in the simulationthen the components can be replaced by a more detailed 3-node model, where the fluid flow rate to the coil may be controlled as opposed to flux. The intake and extract provide a constant volume flowrate of 0.2m^3/s to and from the conditioned space. This corresponds to 5 air changes per hour. The supply air has a constant fresh air content of 20%, with the remainder being re-circulated air from the zone.
Control System
The reception air temperature and humidity is controlled, while the office and roof zones have no control imposed, i.e. they are allowed to free-floa'. Four control loops are imposed on the AHU: pre-heat control, re-heat control, chiller control and humidifier control.
* PRE-HEAT CONTROL.
Sensor Location: pre-heater exit.
Sensed Variable: dry bulb temperature.
Actuator Location: pre-heater.
Actuated Variable: flux.
Control Law: proportional.
Proportional Band. 2 deg C.
Output Range: 0.0 -> 3.5 kW.
Control Period: 07.00 -> 18.00

* HUMIDIFIER CONTROL.
Sensor Location: humidifier exit.
Sensed Variable: dry bulb temperature.
Actuator Location: humidifier.
Actuated Variable: moisture injection.
Control Law: proportional.
Proportional Band. 12% RH.
Output Range: 0.001 -> 0.005 kg/kg.da.
Control Period: 07.00 -> 18.00

* COOLING COIL CONTROL.
Sensor Location: coiling coil exit.
Sensed Variable: dry bulb temperature.
Actuator Location: coiling coil.
Actuated Variable: flux.
Control Law: proportional.
Proportional Band. 2 deg C.
Output Range: 0.0 -> 1.0 kW.
Control Period: 07.00 -> 18.00

* RE-HEAT CONTROL.
Sensor Location: re-heater exit.
Sensed Variable: dry bulb temperature.
Actuator Location: re-heater.
Actuated Variable: flux.
Control Law: proportional.
Proportional Band. 2 deg C.
Output Range: 0.0 -> 3.5 kW.
Control Period: 07.00 -> 18.00

Several other control strategies are available for use with this model:
ahu_flow.on-off-ctl, basic on/off control of the re-heat coil.

ahu_flow.prop-ctl, basic proportional control of humidity and temperature.

ahu_flow.PI-ctl, proportional + integral control of temperature.

When undertaking simulations it is advisable to keep the time step small (<3min) to ensure control system stability.