IDA Early Stage Building Optimization (ESBO) User guide

Transcription

1 IDA Early Stage Building Optimization (ESBO) User guide Version 1.09, Oct 2013

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3 Contents What is IDA ESBO?... 4 How do I use IDA ESBO?... 4 IDA ESBO user interface... 7 Rooms tab... 7 Building tab Start simulation tab Technical description of the default generated systems Purpose and ambition of the default generated systems The default tank models An example of a generated system

4 What is IDA ESBO? IDA ESBO is a simulation program for building design optimization. It allows you to experiment with variations in a building design and to predict the consequences on energy consumption and comfort. IDA ESBO comes in two variants: Template and General. The free Template version allows you to experiment with everything except the building geometry. A number of template geometries are available to choose from. In the General version, you can adapt the model to suit the geometry of a particular project. The ESBO application does not include the effect of heat transmission or air flow between rooms. For projects where these effects are essential to the overall performance of the building, the full IDA ICE application should be used instead. In the next section, a general overview of usage is given. After this, help texts on key input screens are presented roughly in the order they are used. How do I use IDA ESBO? If you are using the Template version, typical rooms and geometry have already been selected, but read this anyway to get an overview of how the application works. The first thing to do is to describe the typical rooms of a building. This is done on the Rooms tab. Typical rooms are rooms that can be expected to have different indoor climate or service systems, e.g. if you have a building with 100 similar south facing offices, you only need to model a single one of these rooms. If you are only modeling a small building, you can describe all individual rooms of the building. However, for a large project, it is always better to model only a selection of rooms such as, for example, South facing single office room, North facing single office room, Open plan office, Conference room, Corridor space etc. Once the typical rooms have been described in terms of geometry on the Rooms tab, you enter the total floor area of each room type in the table at the bottom of the Rooms tab until the whole building floor space has been accounted for. Other significant total areas of the building are then automatically computed. By adapting the typical rooms slightly, e.g. by changing window areas or adding external wall area, you arrive at a model that matches the actual building in the key figures: total window area, total external wall, roof and ground area. These key areas should fall within a few percent of your actual building. After this, the Template and General versions are identical. Once the typical rooms of the building have been defined, you describe internal heat gains for each typical room by selecting (and then possibly editing) usage patterns from a palette of common patterns. Similarly, the indoor climate standard for each typical room is selected. At this stage, you switch to the Building tab. 4

5 In the Building tab, the first thing to do is to select the building location from the drop down list. Next, you open the Defaults form, where typical constructions and window glazing are specified. Note that the default settings will be used for any part of the building where nothing else has been selected in the actual room. For the template buildings no other particular constructions or glazing have been selected, so the default selections will apply. Now, double click on the Ventilation system of the building. By default here, an air handling unit with a return air heat exchanger, a heating and a cooling coil has been defined. If you are happy with this setup, just select the heat exchanger efficiency, the pressure rise of the supply and return fans (or SFP), and the supply air temperature setpoint. If you want a different type of system, drag it in from the palette. Note that air flows in the rooms have already been selected in the Rooms tab. The default central system will be able to supply any amount of tempered air. If you have selected exhaust only ventilation in the typical rooms (or unbalanced supply and return), the makeup air will come from increased infiltration. Also in the Building tab, specify the domestic hot water consumption and the infiltration rate and then we are ready for a first simulation. The rooms of the building are initially equipped with idealized room units for heating and cooling, called Generic units. These will heat and cool the rooms to maintain temperatures within requirements, but are not connected to the water based central system that is described on the Building tab. The Generic units provide heating and cooling to the rooms by directly converting some energy source (such as electricity, fuel or district heating). The systems that are described on the Building tab will always supply any hot or cold water needed by the air handling unit (AHU). When you start, a fixed efficiency boiler and similar chiller are present in the Building tab for this purpose. If you don t want mechanical cooling, remove the cooling systems from your typical rooms as well as the default chiller (that supplies the AHU cooling coil) from the Building tab. The cold storage tank is mandatory and will not be used unless any water based cooling equipment is present in any room or in the air handling unit. To remove the cooling coil from the air handling unit, just set its effectiveness to zero. It is nearly always best to make rough calculations with idealized systems first to compute needed sizes of other types of equipment. To make a first set of simulations, switch to the Simulation tab. The first thing to do here is to simulate a severe winter day (Heating design). This will compute a heating need in all rooms that will later on be useful to select non-idealized room units and central systems. Similarly, if you want to size a cooling system or check for summer overheating, run a summer day simulation (Cooling design). If you are in a truly early stage of the project and have not yet started to think about what particular supply systems to use for the building, go ahead with a whole-year energy simulation. This will enable you to optimize the building envelope first and then turn to a more sophisticated system description. 5

6 Once you are ready to start experimenting with different real system components, first go back to the Building tab. Here you specify the design temperatures of the hot and, optionally, cold water distribution systems. The next stop is the Rooms tab, where you replace the ideal room units with other options from the palette, such as radiators, fan coils or floor heating. In order to select a radiator or similar device, you must both have access to the heating demand of the room and of the system design temperatures. Note that the design power of most components, such as for example the radiator, are given with respect to a rating condition. If the actual temperature conditions differ from these, the emitted maximum power will not match the number that is given. Usually, the default rated conditions are standardized and will match those found in commercial technical data sheets. If you want the maximum power to match the given number, you can manually set the rated conditions to match the water and air temperatures of your simulation. 6

7 IDA ESBO user interface Rooms tab Figure 1 The rooms tab is active when a case is opened. Here the typical rooms of the building are specified. Rooms can be either shoebox shaped, prismatic or have a locked arbitrary geometry that has been imported. In the Template version all rooms have locked prismatic-shaped geometry. Objects in the palette to the left on the screen can be used to replace the default objects in a room. Some objects, such as windows and doors, are inserted directly into the 3D view by dragging them. HVAC system objects and settings are dragged directly into the corresponding place in the form. Most of the default objects can either be removed, e.g. remove the default generic cooler to study a room without cooling, or replaced with other objects with different properties. The generic objects that are described in this help text are always available. In addition to these, there may be objects that represent products of given manufacturers. There may also be combination objects that fulfill more than a single function, for example a four pipe fan coil that can both heat and cool the room. 7

8 Rooms table New room Add a new shoebox shaped room 4 x 2.5 x 2.6 m with default internal wall construction on all surfaces. The geometry of the room is shown in the 3D view and the properties of the room are shown in the fields above. In the Template version this button is unavailable. Rename Change the name of the selected room. Duplicate Add a copy of the selected room. In the Template version this button is unavailable. Remove Remove the selected room. In the Template version this button is unavailable. Rooms summary table All rooms of the building are shown in the table and key figures of the rooms are displayed. The floor area and the room multiplier can be edited. When either one of these are changed, the other figures of the room are updated. The building totals are shown at the bottom of the table. A target row is displayed at the bottom of the table where the actual building key totals can be entered for easy reference. When a room is selected in the table, its geometry and other properties of the room are displayed. Expand table The Rooms summary table is opened in a separate resizable window for easy viewing of a larger number of typical rooms. 3D view Help for 3D view Displays the following text as a tooltip when the mouse is pointed at the button, and in a dialog when the button is clicked: Left mouse button: Click Select object. Selected object is shown in red. Left mouse button: Press down and move mouse Rotate the model. Middle mouse button (or both the left and the right mouse buttons on a two button mouse): Press down and move the mouse Pan the model. Right mouse button: Press down and move the mouse Zoom in/zoom out. Move the mouse upwards to zoom in and downwards to zoom out. The x+, x-, y+, y-, z+, z- buttons create a section through the room. When section is activated, press Ctrl-key, click within the red frame and move the mouse pointer, to move the section. A window, door or surface part can be dragged to a new position. When the window, door or surface part object is selected, press Ctrl-key, click on the object and move the mouse pointer, to move the object. Restore default view Zoom and pan the model so that the entire model is visible and undo any cut of the model. 8

9 x+ Cut the 3D model along the x-axis removing all geometry on the positive side of the cut plane. x- Cut the 3D model along the x-axis removing all geometry on the negative side of the cut plane. y+ Cut the 3D model along the y-axis removing all geometry on the positive side of the cut plane. y- Cut the 3D model along the y-axis removing all geometry on the negative side of the cut plane. z+ Cut the 3D model along the z-axis removing all geometry on the positive side of the cut plane. z- Cut the 3D model along the z-axis removing all geometry on the negative side of the cut plane. Mouse operations Left mouse button: Click Select object. Selected object is shown in red. Left mouse button: Hold down and move mouse Rotate the model. The model is always oriented so that the positive z-axis is up. Left mouse button: At cut, press Ctrl-key, click within red frame, hold down and move mouse Move the cut plane. Left mouse button: Press Ctrl-key, click within selected window or surface part and move mouse Move window/surface part. Middle mouse button (or both the left and the right mouse buttons on a two button mouse): Hold down and move the mouse Move the model up, down, right or left. Right mouse button: Click Open right mouse button menu. Right mouse button: Hold down and move the mouse Zoom in/zoom out. Move the mouse upwards to zoom in and downwards to zoom out. Right mouse button menu: Set focus Set the point around which the model is rotated and towards which it is zoomed. Right mouse button menu: Zoom extents Zoom and pan the model so that the entire model is visible. Geometry Length Length of room, inside measurement [m]. Editable for shoebox shaped rooms. Width Width of room, inside measurement [m]. Editable for shoebox shaped rooms. Height Height of room, inside measurement [m]. Editable for shoebox shaped and prismatic rooms. Edit Open 2D editor to edit shape of prismatic room. Unavailable for of rooms with locked geometry. 9

10 Import Import arbitrary polygon based geometry. The imported geometry will be locked and uneditable. In the Template version this button is unavailable. Orientation Orientation of room with respect to north [ ]. In the Template version this field is unavailable. All rooms can be collectively rotated from the Building tab. Orientation widget Set room orientation by selecting corresponding radio button. In the Template version this control is unavailable. Room systems and settings Internal gains Drag an internal gains object from the palette to the rooms tab. Double click to open the internal gains object, Figure 5. Indoor Climate Standard Drag an indoor climate standard object from the palette to the rooms tab. Double click to open the indoor climate standard object, Figure 6. Heating Drag a heating object from the palette to the rooms tab. Double click to open the heating object, Figure 8. Click the wastebasket to remove the object. Ventilation Drag a ventilation object from the palette to the rooms tab. Double click to open the ventilation object, Figure 14. Click the wastebasket to remove the object. Cooling Drag a cooling object from the palette to the rooms tab. Double click to open the cooling object. Click the wastebasket to remove the object. Removing this object will avoid local room unit cooling, but the room may still be supplied with mechanically cooled air. To remove all cooling, remove also the Cooling object from the Building tab (but not the Cold storage). 10

11 Figure 2 Window Drag a window from the palette to a surface of the room in the 3D view, Figure 2. Double click to open the window object, Figure 24 and Figure 25. Right click and choose Delete to remove the window. Right click and choose Duplicate to insert a copy of the window, slightly shifted from the original position. When a window is added to a surface with internal construction, the surface is assigned the default external construction. A selected window can be moved by holding down the ctrlkey and dragging the window to a new position, which can be on another wall. Door Drag a door from the palette to a surface of the room in the 3D view. Double click to open the door object, Figure 26. Right click and choose Delete to remove the door. Right click and choose Duplicate to insert a copy of the door, slightly shifted from the original position. When a door is added to a surface with internal construction, the surface is assigned the default external construction. A selected door can be moved by holding down the ctrl-key and dragging the door to a new position, which can be on another wall. Surface part: part of a surface with different construction and/or boundary conditions. Drag a surface part from the palette to a surface of the room in the 3D view, Figure 3. Double click to open the surface part object, Figure 27. Right click and choose Delete to remove the surface part. Right click and choose Duplicate to insert a copy of the surface part, slightly shifted from the original position. 11

12 A selected surface part can be moved by holding down the ctrl-key and dragging the surface part to a new position, which can be on another wall. These operations are not available in the Template version. Figure 3 Wall construction Drag a wall construction from the palette to a surface of the room in the 3D view. Double click on the surface in the 3D view to open the wall construction dialog. Right click and choose Delete to remove the construction assignment. When a wall construction is removed, the surface is assigned the default internal construction, unless there is a window or door on the surface, in which case it is assigned the default external construction. To specify a surface as default external, internal or ground construction, drag the default external, internal or ground construction object on to it from the palette. 12

13 Editing room Figure 4 Dialog for editing the rectangular shape of a room into an arbitrary polygon. The dialog is opened by clicking the Edit button on the rooms tab. The perimeter of the room is shown as a polyline. A polyline consists of line segments and break points, the latter marked by small rectangles. The polyline can be edited as follows: - Its breakpoints can be dragged to the desired positions for the room s corners. - Its line segments can be dragged to the desired positions for the room s walls. - A new breakpoint can be introduced by clicking on or close to the line. - An existing breakpoint can be deleted by clicking on it. 13

14 - Breakpoints for non right-angled corners can be introduced by holding down the ctrl-key and simultaneously clicking on a line segment. Internal gains Figure 5 Dialog defining the internal gains in the room. Equipment Dry convective heating power from appliances in the room [W/m 2 ]. Click hyperlink to open dialog for setting other equipment details. Schedule Schedule determining when equipment is on [selection from available resources]. Click hyperlink to open schedule dialog. Occupants Number of occupants that load the room (dry and wet) [number/m 2 ]. Click hyperlink to open dialog for setting other occupant details. Schedule Schedule determining when occupants are present [selection from available resources]. Click hyperlink to open schedule dialog. Lights Rated input power when lights are on [W/m 2 ]. Click hyperlink to open dialog for setting other light details. Schedule Schedule determining when lights are on [selection from available resources]. Click hyperlink to open schedule dialog. 14

15 Basic indoor climate settings Figure 6 Dialog defining a variant of the indoor climate standard in the room. Heating setpoint The air temperature that heating units attempt to maintain [ C]. Cooling setpoint The air temperature that cooling units attempt to maintain [ C]. Method Type of air quality measure [CO 2 limit]. CO 2 limit - maintain CO 2 below the limit. Limit The air quality setpoint. Generic heater Figure 7 The generic heater has by default unlimited capacity. It heats the room directly, using the given energy source, i.e. it does not rely on any central systems that have been defined on the Building tab. The 15

16 generic heater is normally used in the initial stages, to find required system capacity. By default, 40% of the heat is emitted as long wave radiation. This ratio can be changed in the Building defaults form. Water based radiator or convector Figure 8 Device type Type of radiator or convector [selection from available resources]. Click hyperlink to access radiator parameters that are stored in the database. Size Size radiator/convector based on [power, front area]. power Emitted power at rating conditions. [W/m 2 ]. Copy Copy data from previous room unit heating calculation. Design power is shown in the (grey) input field. Corresponding area is shown in the (grey) front area field. front area Front area of radiator/convector [m 2 ]. 16

17 Radiator rating conditions Figure 9 Room and water temperatures at which the given power radiator power will be emitted. Note that actual radiator capacity is strongly dependent on these. 17

18 Air to air, non-ducted, heat pump Figure 10 Model for an air-to-air direct expansion on-off controlled unit for heating of room air. At the given rating condition (press button to see), the model will yield given total power and COP, if it is physically possible. If a physically unrealistic COP is given, the model may yield the required performance at the actual rated point, but may render completely erroneous results at other operating points and may also become numerically unstable. It is generally not recommended for most users to change any other parameter than the total heating power. Away from the rated point, the performance will be determined by the additionally specified parameters. With the exception of compressor parameters, the input data are measurable quantities but may not always be made available by equipment manufacturers. If parameters have been identified 18

19 with respect to measured data from a real device, the model will predict the performance over the whole operating range within the accuracy of a few percent, typically around one. Floor heating Figure 11 The floor heating circuit is assumed to cover the whole floor of a room. Net design mass flow into the circuit from the hot tank is given in terms of a design power and temperature difference. Note that all of this power may not be accessible to the room, if for example the pipes have been located in the middle of an insulation layer. If the water temperature from the hot tank (that is specified in the Building tab, Heat Distribution system) is unsuitably high for direct injection into a floor coil circuit, the constant coil mass flow option should be chosen (default). The coil location in the slab may be critical to the resulting heat emission. Overall heat transfer from the pipes to the surrounding material is governed by the H-water-pipe-fin parameter. Some approximate 19

20 values are given in the form. For more accurate simulations, measurement data or computational results from a more detailed simulation model should be used. Heated beam Figure 12 Given power is extracted from the water when temperatures are according to the rating conditions and air flow is at the given design air flow. Some power must also be emitted at zero air flow, otherwise the model may become unstable. If the design air flow is lower than the total supply air flow to the room, the surplus air is injected into the room without passing the beam. Figure 13 20

21 Generic ventilation Figure 14 Dialog defining a variant of the ventilation in the room. Type Type of ventilation system [Constant Air Volume, Variable Air Volume]. supply Mechanical supply airflow for CAV systems [l/s m 2 ]. return Mechanical return airflow for CAV systems [l/s m 2 ]. min Minimum airflow at VAV [l/s m 2 ]. max Maximum airflow at VAV [l/s m 2 ]. control Control of VAV system [ CO 2, Temperature, Temperature + CO 2 ]. Generic cooler Figure 15 The generic cooler has by default unlimited capacity. It cools the room by convection, using the given energy source, i.e. it does not rely on any central systems that have been defined. The generic cooler is 21

22 normally used in the initial stages, to find required system capacity. By default, the cooling coil is assumed to hold 15⁰C and may remove moisture from the air. This temperature can be changed in the Building defaults form. Water based cooling device Figure 16 Device type Type of cooling device [selection from available resources]. Click hyperlink to edit basic device parameters. Size Size cooling device based on [power, front area]. power Emitted power [W/m 2 ]. Copy Copy data from previous room unit cooling calculation. Design power is shown in the (grey) input field. Corresponding area is shown in the (grey) front area field. front area Front area of cooling device [m 2 ]. Rating conditions Figure 17 22

23 Temperature conditions at which the device will remove the specified amount of heat. Air to air, non-ducted, air conditioner Figure 18 Model for an air-to-air direct expansion on-off controlled unit for cooling and dehumidifying room air. At the given rating condition (press button to see), the model will yield given total power and EER (cooling COP), if it is physically possible. If a physically unrealistic COP is given, the model may yield the required performance at the actual rated point, but may render completely erroneous results at other operating points. It is generally not recommended for most users to change any other parameter than the total cooling power. 23

24 Away from the rated point, the performance will be determined by the additionally specified parameters. With the exception of compressor parameters, the input data are measurable quantities but may not always be made available by equipment manufacturers. If parameters have been identified with respect to measured data from a real device, the model will predict the performance over the whole operating range within the accuracy of a few percent, typically around one. Figure 19 Rating conditions, by default according to EN Floor cooling Figure 20 See help text on p. 19 for floor heating. 24

25 Chilled beam Figure 21 Given power is absorbed by the water in the beam when temperatures are according to the rating conditions and air flow is at the given design air flow. Some power must also be absorbed at zero air flow, otherwise the model may become unstable. If the design air flow is lower than the total supply air flow to the room, the surplus air is injected into the room without passing the beam. Figure 22 25

26 Heating/cooling floor Figure 23 Object for combined heating and cooling by the same floor coil. See help text on p. 19 for floor heating. 26

27 Window Figure 24 Form for defining a window on a surface. 27

28 Frame fraction The unglazed area of the window divided by the whole window area, defined by the outer frame measures [%]. Glazing Choice of glass configuration, includes g, T, Tviz and U-value for the glass [selection from available resources]. Click hyperlink to open glazing dialog. Integrated shading Choice of curtains or blinds [selection from available resources]. Click hyperlink to open integrated shading dialog. External shading Include external window shading. When checked the image of the window, Figure 24, changes to show an awning, Figure 25. Opening control Selection of control strategy for window opening. [Schedule, PI temperature control + schedule] Schedule - The opening is controlled by time schedule (or not controlled at all) PI temperature control + schedule - The opening is controlled by air temperatures (both internal and external) in the range from 0 (fully closed) to the value given by the schedule Opening schedule Schedule for degree of window opening. 0 = fully closed, 1 = fully open. X Position in x-direction [m]. Y Position in y-direction [m]. Width The window s extension along the x-direction (frame outside measurement) [m]. Height The window s extension along the y-direction (frame outside measurement) [m]. Recess depth The distance between the window outer pane and the façade surface [m]. Awning width The total width of the awning [m], see Figure 25. Awning height The total height of the awning projected on the façade [m], see Figure 25. Awning extension The largest distance the sunblind is from the façade surface [m], see Figure 25. Awning, mounting distance above window Distance between the awning bracket and the window recess [m], see Figure

29 Figure 25 29

30 Door Figure 26 Dialog defining a door on a surface. Construction Construction of door [selection from available resources]. Click hyperlink to open construction dialog. X Position in x-direction [m]. Y Position in y-direction [m]. Width The door s extension along the x-direction [m]. Height The door s extension along the y-direction [m]. Surface part Figure 27 30

31 Dialog defining a surface part on a surface. Construction Construction of surface part [selection from available resources]. Click hyperlink to open construction dialog. X Position in x-direction [m]. Y Position in y-direction [m]. Width The surface part s extension along the x-direction [m]. Height The surface part s extension along the y-direction [m]. 31

32 Building tab Figure 28 The building tab is used to specify both general information about the simulation and the HVAC systems that serve the building. Similarly to the room tab p. 7, the default objects for HVAC systems and settings may be replaced by those available on the left hand side bar palette. Most combinations of HVAC system components will automatically be connected into meaningful systems. See p. 68 for a more technical description of the systems that are generated. Project data Project data Click to open project the data object, an object for documentation of the simulation case and the current choice of parameters. Project data is written on reports etc. Global data Location Location of the building [selection from available resources]. The object contains a reference to a location and a climate file. Click hyperlink to open location dialog. Wind profile Choice of wind profile object [selection from available resources]. Click hyperlink to open wind profile dialog. 32

33 Rotate building Angle to rotate building incrementally [ ]. Clockwise Click to rotate the building clockwise by the specified angle around the center of the building. Counter-clockwise Click to rotate the building counter-clockwise by the specified angle around the center of the building. Defaults Click to open defaults form, which contains defaults for all rooms, Figure 29. Thermal bridges Click to open thermal bridges object, which contains coefficients for calculation of loss factors for thermal bridges in rooms, Figure 30. Ground properties Click to open ground properties object, which contains model and parameters for temperature conditions below the building, Figure 31. Infiltration Click to open infiltration object, which contains method and parameters for building air leakage, Figure 32. Extra energy and losses Click to open extra energy and losses object, which contains information about extra energy consumers of the building that do not take part in the building heat balance, such as external lighting, Figure 33. Building 3D and shading Click to open building 3D and shading window, Figure 41, Figure 42 and Figure

34 Defaults Figure 29 Input given here will be used unless other data has been given in the room or subsystem. 34

35 External walls Construction for external walls lacking descriptions in the room. Internal walls Construction for internal walls lacking descriptions in the room. Internal floors Construction for internal floors lacking descriptions in the room. Roof Construction for roofs lacking descriptions in the room. External floor Construction for floor slabs lacking descriptions in the room. A ground insulation layer is normally described as part of the ground structure. Glazing Glazing for windows lacking descriptions in the window. Door construction The default construction for doors. The default setting for this parameter is "[use wall construction]" which means that there will be no special treatment of wall material. Integrated window shadings The default shading device for the window. Default heating Default type of heating for plant components and ideal room units. Heating COP Default heating efficiency. Default cooling Default type of cooling for plant components and ideal room units. Cooling COP (EER) Default cooling efficiency. Ideal cooler coil temperature [ C] Ideal heater radiative fraction Ideal heater emission efficiency Ideal cooler emission efficiency IDA resources Open form containing the IDA-resources currently or previously used in this project. Database Open the IDA database. 35

36 Thermal bridges Figure 30 These coefficients are used to calculate the loss factors in thermal bridges in rooms. The total loss factor for a room is calculated as the sum of loss factors in bridges created by different construction elements. The coefficients are given per unit of element size (in most cases per meter). The sizes of elements are calculated from room geometry. 36

37 Ground properties Figure 31 Ground layers under basement slab Ground layers under slab down to constant temperature. Ground layer outside basement walls Ground layers outside wall to ambient temperature. The ground layer under the basement floor is connected to a constant temperature, which is computed as the mean air temperature of the selected climate file. The layers around the basement walls are coupled to a facade object for crawl space, which is kept at ground surface temperature. Note that no 2D or 3D effects are modelled for either of these couplings. Infiltration Figure 32 Data in the infiltration form is used to specify unintentional air flows over the building envelope without having to visit each room. Constant envelope air flows to and from each room are introduced. 37

38 Extra energy and losses Figure 33 In this form, losses from HVAC distribution systems and additional energy use items (external lighting etc.) are specified. Distribution System Losses are specified to account for leakage from pipes and ducts that pass through the building without having to describe their exact path and insulation properties. For water circuits, the sign is positive when heating the room for DHW and heat, and positive when cooling for cold water circuits. The loss from air ducts is defined as positive when the duct is cooler than the room. Duct losses include both thermal conduction and air leakage losses, although the actual loss of mass through the duct wall is not modeled. Duct losses take account of actual temperature difference between the duct system and rooms, while water circuit losses are independent of actual temperatures. Units for heat and cold distribution may be changed for convenience. Rough estimates of possible loss levels are provided for convenience via sliders, but these levels vary greatly between countries. A given percentage of the heat (or cold) from each distribution system is deposited to the room heat balance. Remaining heat is simply lost to ambient. 38

39 Any number of Additional Energy Use items may be specified (right click to rename them). This is energy which should be accounted for in total supplied energy, but does not enter the building heat balance. Ice melting equipment or external lights are examples. For each item, both an absolute and a per-floor-area contribution may be given. The total of both is displayed for convenience. Each item must also refer to a schema and an energy meter. Distribution systems Air Drag an air distribution system object from a palette to the building tab. Double click to open air distribution system object, Figure 34. Figure 34 The air distribution object contain general settings for the mechanical ventilation system. When applicable, these parameters will be referenced by the selected air handling unit. They may also be used elsewhere. Heat Drag a heat distribution system object from a palette to the building tab. Double click to open heat distribution system object, Figure

40 Figure 35 The hot water distribution object contains general settings for the water based heating system. These parameters will be used for the generation of a plant model. Three points may be given on the curve for supply temperature as function of ambient temperature. All water based heating units in the rooms will be fed with the same water temperature. A separate setpoint is available for hot water to the air handling system. Cold Drag a cold distribution system object from a palette to the building tab. Double click to open cold distribution system object, Figure

41 Figure 36 The cold water distribution object contains general settings for the water based cooling system These parameters will be used for the generation of a plant model. Three points may be given on the curve for supply temperature as function of ambient temperature. All water based heating units in the rooms will be fed with the same water temperature. A separate setpoint is available for hot water to the air handling system. Domestic hot water Drag a domestic hot water object from a palette to the building tab. Double click to open domestic hot water object, Figure 37. Figure 37 Domestic Hot Water Use may be specified here using different units. Note that when a unit that includes the number of building occupants is used, the relevant number of occupants should be set here as well. The Number of occupants field is by default bound to the sum of all defined occupant thermal 41

42 gains. However, in many situations, this number is quite different from a relevant "water consuming occupant", for example a conference room will hold a lot of occupant loads that have their normal "base" in some other room. Energy Electricity rate Drag an electricity rate object from a palette to the building tab. Double click to open electricity rate object, Figure 38. Fuel rate Drag a fuel rate object from a palette to the building tab. Double click to open fuel rate object, Figure 38. Note that the pricing is given with respect to fuel heating value, not consumed mass or volume. District heating rate Drag a district heating rate object from a palette to the building tab. Double click to open district heating rate object, Figure 38. District cooling rate Drag a district cooling rate object from a palette to the building tab. Double click to open district cooling rate object, Figure 38. Figure 38 CO 2 emission factors Drag a CO 2 emission factors object from a palette to the building tab. Double click to open CO 2 emission factors object, Figure 39. Figure 39 42

43 The CO2 emission factors are used to determine the amount of CO2 that will be released into the atmosphere as the energy source is used. For Fuel the reference energy is counted in terms of fuel heating value. Primary energy factors Drag a primary energy factors object from a palette to the building tab. Double click to open primary energy factors object, Figure 40. Figure 40 The primary energy factors are used to determine the amount of so called primary energy that will be used for delivery of each unit of each category of energy. Many countries have politically determined primary energy factors that are used to compare the relative environmental impact of different systems. Central systems Solar thermal Drag a solar thermal object from a palette to the building tab. Double click to open solar thermal object. Click the wastebasket to remove the object. Photovoltaics Drag a photovoltaics object from a palette to the building tab. Double click to open photovoltaics object. Click the wastebasket to remove the object. Ventilation Drag a ventilation object from a palette to the building tab. Double click to open ventilation object. Click the wastebasket to remove the object. Hot storage Drag a hot storage object from a palette to the building tab. Double click to open hot storage object. Click the wastebasket to remove the object. Cold storage Drag a cold storage object from a palette to the building tab. Double click to open cold storage object. Click the wastebasket to remove the object. Topup heating Drag a topup heating object from a palette to the building tab. Double click to open topup heating object. Click the wastebasket to remove the object. Base heating Drag a base heating object from a palette to the building tab. Double click to open base heating object. Click the wastebasket to remove the object. 43

44 Cooling Drag a cooling object from a palette to the building tab. Double click to open cooling object. Click the wastebasket to remove the object. Ambient heat exchange Drag an ambient heat exchange object from a palette to the building tab. Double click to open ambient heat exchange object. Click the wastebasket to remove the object. Ground heat exchange Drag a ground heat exchange object from a palette to the building tab. Double click to open ground heat exchange object. Click the wastebasket to remove the object. All ambient or ground heat exchangers are connected to a brine loop. The brine loop will always be connected to heat exchangers in the hot and cold tanks. This way, a ground heat exchanger can directly cool the building without the assistance of a chiller. However, should a Brine to water chiller be dragged in, its condenser will also be cooled by the brine loop (and the resulting hot brine may even be warm enough to be utilized directly in the hot tank). When two or more central system boxes are graphically connected the added system covers the function of both boxes. Select Plant details under Requested output in the Simulation tab in order to see the time-evolution of key Central system variables. Building 3D and shading The building 3D and shading window is opened by clicking Building 3D and shading on the building tab. Rooms In the building 3D and shading window, rooms can be given a position in 3D space to form a sensible building. Drag rooms from the table in the Rooms tab to the building 3D and shading window, Figure 41. In the 3D view, the room will move in the x-y plane. Hold down the shift-key to move the room in the z- direction. To reposition a room: select it, hold down the ctrl-key and drag it. By default all rooms of the building are placed at the origin. The rooms do not shade windows or solar panels. 44

45 Figure 41 Shading objects In the building 3D and shading window, shading objects can be added to produce additional shading of windows and solar panels. Drag shading objects from the palette to the building 3D and shading tab, Figure 42. Right click and choose Delete to remove the shading object. Right click and choose Duplicate to insert a copy of the shading object, slightly shifted from the original position. A selected shading object can be moved by holding down the ctrl-key and dragging the shading object to a new position. The shading-object will move in the x-y plane. Hold down the shift-key to move the shading object in the z-direction. Right click and choose Edit to edit the shape of the shading object, Figure

46 Figure 42 46

47 Figure 43 When in edit mode, Figure 43, the shading object can be modified as follows: - To edit the shape and location of the shading object, place the cursor over a handle, click the left mouse button, and drag the handle. - To move the entire shading object, place the cursor over the shading object, in-between two handles, click the left mouse button, and drag the shading object. The shading object follows the cursor while remaining fixed in the z-axis. - To move the shading object along the z-axis, hold down the shift-key while moving the mouse. - To rotate the shading object around the z-axis, place the cursor above the shading object, hold down the shift-key and the middle mouse button, and move the mouse. - To scale the shading object (bring the handles closer/further apart), place the cursor above the shading object, hold down the shift-key and the right mouse button, and move the mouse. 47

48 - To insert a new handle, hold down the ctrl-key, and click the left mouse button. - To remove a handle, place the cursor above the handle, hold down the ctrl-key, and click the right mouse button. Exit the edit mode by clicking the right mouse button and choosing Done or Cancel from the right mouse button menu. Solar panel If solar thermal or photovoltaics systems have been added to the building, these will be visible in the building 3D and shading window as solar panels, Figure 44. The solar panels can be given a sensible position in 3D space by holding down the ctrl-key and dragging the panel to a new position. The panel will move in the x-y plane. Hold down the shift-key to move the panel in the z-direction. Solar panels are shaded by other shading objects. Solar panels themselves shade other solar panels and windows if they have been moved to a sensible position, i.e. if they are left at the origin they will not shade. 48

49 Figure 44 Help for 3D view Displays the following text as a tooltip when the mouse is pointed at the button, and in a dialog when the button is clicked: Left mouse button: Click Select object. Selected object is shown in red. Left mouse button: Press down and move mouse Rotate the model. Middle mouse button (or both the left and the right mouse buttons on a two button mouse): Press down and move the mouse Pan the model. Right mouse button: Press down and move the mouse Zoom in/zoom out. Move the mouse upwards to zoom in and downwards to zoom out. The x+, x-, y+, y-, z+, z- buttons create a section through the building. When section is activated, press Ctrl-key, click within the red frame and move the mouse pointer, to move the section. 49

50 A room, shading object or solar panel can be dragged to a new position. When the room, shading or solar panel object is selected, press Ctrl-key, click on the object and move the mouse pointer, to move the object. The object will move in the x-y plane. Hold down the Shift-key to move the object in the z-direction. When in edit mode, a shading object can be modified as follows: To edit the shape and location, place cursor over a handle, click left mouse button, drag handle. To move the entire object, place cursor in-between two handles, click left mouse button, drag object. The object will move in the x-y plane. Hold down the Shift-key to move the object in the z-direction. To rotate the object in the x-y plane, place cursor over object, hold down Shift-key and middle mouse button, move the mouse. To scale the object (bring the handles closer/further apart), place cursor over object, hold down Shift-key and right mouse button, move the mouse. To insert a new handle, hold down Ctrl-key, click left mouse button. To remove a handle, place cursor over the handle, hold down Ctrl-key, click right mouse button. Restore default view Zoom and pan the model so that the entire model is visible and undo any cut of the model. x+ Cut the 3D model along the x-axis removing all geometry on the positive side of the cut plane. x- Cut the 3D model along the x-axis removing all geometry on the negative side of the cut plane. y+ Cut the 3D model along the y-axis removing all geometry on the positive side of the cut plane. y- Cut the 3D model along the y-axis removing all geometry on the negative side of the cut plane. z+ Cut the 3D model along the z-axis removing all geometry on the positive side of the cut plane. z- Cut the 3D model along the z-axis removing all geometry on the negative side of the cut plane. 50

51 Generic solar thermal Figure 45 Select a solar collector model from the drop down list. Either total area or number of units of the selected type can be specified. 51

52 Generic photovoltaics Figure 46 PV can be specified in terms of area and overall efficiency. All generated electricity shows up as a negative contribution in the delivered energy report. 52

53 Standard air handling unit Figure 47 The standard air handling system consists of the following components Figure 47: supply air temperature setpoint controller (1), exhaust fan (2), heat exchanger (3), heating coil (4), cooling coil (5), supply fan (6), schedule (7) for operation of both fans and a schedule for the operation of the heat exchanger (8). The unit provides temperature-controlled air at a given pressure. Some key parameters of individual components are presented in the form; open them to edit. The supply air temperature setpoint is set in the Air distribution system dialog opened by double-clicking on the Air distribution control box (1). 53

54 Return air only AHU Figure 48 See section on Standard air handling unit. 54

55 AHU with electrical heating coil Figure 49 See section on Standard air handling unit. Generic topup heater Figure 50 The top-up heater is employed when temperature in the hot tank drops more than 2⁰C below the highest requested temperature. Energy source as well as a constant production efficiency (or COP) can be selected. The total capacity can optionally be limited. 55

56 Ambient air to water heat pump Figure 51 Figure 52 Model for an air-to-water, on-off controlled, unit for water heating. At the given rating condition (press button to see dialog below), the model will yield given total power and COP. It is generally not recommended for most users to change any other parameter than the total heating capacity. 56

57 Away from the rated point, the performance will be determined by the additionally specified parameters. These are measurable quantities but may not always be made available by equipment manufacturers. If parameters have been identified with respect to measured data from a real device, the model will predict the performance over the whole operating range within the accuracy of a few percent, typically around one. Figure 53 Brine to water heat pump 57

58 Figure 54 Model for a brine to water on-off controlled unit for hot water heating. At the given rating condition (press button to see), the model will yield given total power and COP. It is generally not recommended for most users to change any other parameter than the total heating capacity. Away from the rated point, the performance will be determined by the additionally specified parameters. Most of these are measurable quantities but may not always be made available by equipment manufacturers. If parameters have been identified with respect to measured data from a real device, the model will predict the performance over the whole operating range within the accuracy of a few percent, typically around one. The cold (evaporator) side of the Brine to water heat pump, will automatically be connected to the brine circuit. In most situations, some ambient or ground heat exchanger must also be added by the user to the brine loop in order to collect heat for the heat pump. This is done by simply dragging such a component into the form. The cold side of the heat pump will always be connected to a heat exchanger in the cold tank and thus provide free cooling to the building whenever this is possible. 58

59 Figure 55 Generic hot water tank Figure 56 Some hot water storage facility is required in an Esbo simulation. See further discussion about the tanks and Esbo plant models on p. 68. If you do not want to consider a real water tank, select the volume to be small with respect to the size of the modeled system. The tank will then represent general mass of the piping system and connected devices. If the tank size is too small, the model is likely to have numerical difficulties. 59

60 Generic cold water tank Figure 57 Some cold water storage facility is required in an Esbo simulation. See further discussion about the tanks and Esbo plant models on p. 68. If you do not want to consider a real water tank, select the volume to be small with respect to the size of the modeled system. The tank will then represent general mass of the piping system and connected devices. If the tank size is too small, the model is likely to have numerical difficulties. Generic chiller Figure 58 Energy source as well as a constant production efficiency (or cooling COP) can be selected. The total capacity can optionally be limited. 60

61 Brine to water chiller Figure 59 Model for a brine to water on-off controlled unit for water cooling. At the given rating condition (press button to see), the model will yield given total power and EER (cooling COP). It is generally not recommended for most users to change any other parameter than the total cooling capacity. Away from the rated point, the performance will be determined by the additionally specified parameters. These are measurable quantities but may not always be made available by equipment manufacturers. If parameters have been identified with respect to measured data from a real device, the model will predict the performance over the whole operating range within the accuracy of a few percent, typically around one. The hot (condenser) side of the Brine to water chiller, will automatically be connected to the brine circuit. In most situations, some ambient or ground heat exchanger will must also be connected to the brine loop in order to dispose of the waste heat. This is done by simply dragging such a component into the form. The hot side of the chiller will always be connected to a heat exchanger in the hot tank and thus provide free heating to the building when possible. 61

62 Figure 60 62

63 Heat exchange with given temperature source Figure 61 The model is used to specify the option of heat exchange with a temperature source with a practically infinite capacity, such as sea water or in some approximations the ground. In place of the default constant temperature, a schedule that prescribes the temperature variation as a function of time can be given. The given power, temperature difference and pressure loss are used to determine sizes of the heat exchanger and associated pumps and pipes. Pumps are regarded to be capacity controllable down to zero flow with given constant efficiency. Dry or wet air to brine heat exchanger 63

64 Figure 62 Model for a fan assisted ambient heat exchanger. In heat production mode, condensation may occur and therefore a wet coil rating point is required. The efficiency is defined with respect to an apparatus dew point which is the average of entering and leaving brine temperature. Wet coil leaving air conditions will lie on a straight line between entering conditions in the psychometric chart and the apparatus dew point. The dimensionless distance along this line is defined as the efficiency. 64

65 Start simulation tab Figure 63 Results Requested output Select Open dialog to specify what diagrams and reports that will be created during the simulation. Note in particular the Plant details option, that will provide the time-evolution of key Central system variables. Simulation Heating design Setup Open dialog to define key parameters to be applied in the calculation. Heating design Run Run heating design simulation. Cooling design Setup Open dialog to define key parameters to be applied in the calculation. Cooling design Run Run cooling design simulation. Energy Setup Open dialog to define key parameters to be applied in the calculation. Energy Run Run energy simulation. Standard level Available only if the full IDA ICE application is accessible. Build model Click to build and open an IDA ICE model of the system. 65

66 Results tab Figure 64 The Results tab is shown automatically, after a completed simulation. Results summary table All rooms of the building are shown in the table and key results of the rooms are displayed. Use Summary, Heating design and Cooling design radio buttons to switch between results. Report The results summary table is exported to Excel. Expand table The results summary table is opened in a separate resizable window of easy viewing of more rooms and columns than can fit in the results tab table. Detailed results A list of all result objects requested before the simulation. Modified The time when the model was last changed. Only shown if the model was changed after the latest simulation. Saved The time when the case was last saved on disk. Simulated The time when the latest simulation was run. 66

67 Make report When pressed, the input data and results are combined into a single Word document. Implemented only for Word 2000 or later. 67

68 Technical description of the default generated systems In the Building tab, many different system configurations can be described by dragging in various components. Based on these, systems are automatically generated in the standard level of IDA ICE. For users who have access to the IDA ICE application, these systems can be inspected in detail, and if an Expert edition license is available, the systems can also be reconnected and configured. In this section, we describe the principles for the construction and control of the default systems. Note that combination components, for example a solar collector and tank combination from a particular manufacturer, may lead to other system configurations that may or may not be compatible with the available generic set of components. For example, if a solar-collector and tank combination only allows built-in electrical top-up heating, both the hot tank, the solar thermal, the base heating and the top-up heating slots will be occupied by the combination system and no other systems will be allowed to feed into the hot water tank. Here, the narrative will rely on system schematic diagrams as displayed in the Standard level. For a user with access to the full IDA ICE application, these can be reached by the Build model button on the Start Simulation tab. Open the Plant model from the General tab in the full application. Purpose and ambition of the default generated systems In economically feasible real systems many compromises must be made. The total number of valves, pumps and connections must be reasonable and control logic must not be overly complex. In contrast, the purpose of the Esbo default systems is to exploit all significant energy flows based on a minimum of input data from the user even if the physical components needed are not justifiable in a real system. The generated systems are technically realistic but might, at least for smaller installations, contain too many parts to be economically attractive for realization in real life. Furthermore, the control systems employed are extraordinarily decentralized. In order to avoid the combinatorial explosion of having to define a central control system for each possible system configuration, each subsystem is maximally self sufficient. A flow controller for, e.g., a ground source circuit will simply check when it is possible to deliver heat (or cold) and does this until it is not energywise economical to continue (when pumping costs will exceed the benefits). Long-term control strategies, for example to try to seasonally balance a large thermal store, is out of scope of the automatically generated default systems. Whenever the short-term benefit of a certain flow is in place, the flow will be activated. The default tank models All default generated systems are centered around two stratified water tanks, one for hot and one for cold water. These two tanks are mandatory for most system combinations, also for situations where a real system would not include a tank. Furthermore, the tanks are by default equipped with valves that will allow each entering and exiting flow to be made at the optimal height in the tank. This way, minimal 68

69 buoyant mixing will occur. Real tanks exist that behave in a similar fashion, using for example heat lance technology. For situations where a storage tank is not part of the concept to be investigated, the volume of the mandatory tanks can be set fairly small with respect to surrounding systems, but not to zero. The tanks can then be thought of as temperature switchboards that minimize the amount of temperature mixing in the system. Tank volume would then represent the thermal mass of the actual HVAC system. The default height to diameter ratio (shape factor) of the tanks is set to 5, representing a fairly tall tank with, correspondingly, only a small amount of conduction between the (default) ten water layers. In order to create a less ideal tank and ultimately approaching a completely mixed tank, the shape factor can be set smaller, so that conduction will even out temperature differences between layers. When working at the Advanced level, it is possible to turn off the ideal heat lance feature of the tanks and select fixed vertical positions for tank ports. The model will then automatically compute buoyant mixing An example of a generated system Figure 65 shows an example of how the building tab may be populated with models. Some model has been chosen for each of the possible functions. Brine to water vapor compression machines have been defined for base heating as well as for cooling. Both ground heat exchange and ambient heat exchange have been defined. 69

70 Figure 65 Figure 66 shows the generated system at the Advanced level of IDA ICE. We will go through and explain each major subsystem below. 70

71 Figure 66 Organized around the two water tanks, the top one for heat and bottom one for cold storage, are the various circuits that draw or feed tempered water from and to the tanks. Let us start with the client circuits to the right, starting from the top right corner with the DHW circuit. Domestic hot water is drawn from the hot tank, by the leftmost PMT-object, which has a mass flow signal into it that gives the required DHW mass flow. The make-up water from the water mains is furnished by the rightmost PMT-object and a given temperature (which is computed to be the yearly average temperature of the current climate file). Each client circuit, including this one, feeds a temperature setpoint into the tank. In this case this is the temperature setpoint for the DHW (55⁰C). As a simplification, no separate tank-in-tank has been defined for the DHW in the default configuration. The heat exchange between DHW and surrounding water is regarded to be infinite and immediate. The meter objects to the top right are used to record results about DHW production. Next below is the AHU hot water circuit, which is connected via a pump to the air handling unit, providing it with heated water at given pressure and temperature. Similarly as for the DHW, a temperature setpoint (60⁰C in the example) informs the tank about the temperature that is required by 71