glazed alternatives)
5 Description of the building model
5.1 Description of the reference building
5.1.1. Geometry of the building
The reference building is a 6 storey building as shown in Figure 5.1. In terms of geometry and installations, the fl oors 1, 2, 3, 4, and 5 are com-pletely identical. However, the fl oors 1-4 are connected (fl oor, ceiling) with other internal zones of the building, while the roof of the 5th fl oor is
connected to the outside and the ground fl oor is connected to the ground (i.e. there is no basement).
connected to the outside and the ground fl oor is connected to the ground i.e. there is no basement.
Figure 5.1 View of the reference building.
The height of the building is 21m, the length 66 m and the width 15.4 m.
Architectural drawings (fl oor plans, cross sections, facades) are presented in Appendix C. The room height is 2.7 m and the distance between in-termediate fl oors is 3.5 m. There is a suspended ceiling. The total fl oor area is 6177 m2 (BRA usable fl oor area i.e. fl oor area inside exterior walls) and 5448 m2 (LOA non-residential/premises fl oor area). The total area (on the inside including the window area and the area covered by interior walls and intermediate fl oors) of each of the long façades is 1386 m2 and that of the short façades 327.6 m2. Each opaque (wall) area is 957 m2 and 224 m2 respectively. The window area (including the frames) is 429 m2 (30.9% of the facade) and 104 m2 (31.6%) respectively (total window area
= 31%). The roof area inside the exterior walls is 1030 m2.
5.1.2. Offi ce layouts
Two different common fl oor layouts were designed, one with cell-type offi ces and one with open plan offi ces. In practice an offi ce building of-ten has a mixture of these two plan types. In order to simplify the input model and thus reduce the time of simulation, it is important to create as
few thermal zones as possible. On the other hand, the assumptions made should not infl uence the accuracy of the results or limit the output of the simulations. For the six-storey reference building, 3 different fl oor types are assumed, each one with several thermal zones (Figures 5.2 and 5.3).
The zones were chosen to represent different kinds of rooms with differ-ent oridiffer-entations. Adiabatic conditions were assumed for the ceiling of the ground fl oor, for the ceiling and fl oor of the 1st fl oor and for the fl oor of the 2nd fl oor. In this way it is assumed that below and above fl oors 1, 2, 3 and 4 there are identical zones. This is partly correct, since below the 1st and above the 4th fl oor the zones are not exactly the same. However, since the temperatures on all the fl oors are very similar, the infl uence of the connections plays a minor role. For the total energy use the simulated energy use of the 1st fl oor is multiplied by the factor 4.
Figure 5.2 Cell type offi ce building as modelled in IDA ICE 3.0 showing the simulated zones.
Figure 5.3 Open plan type offi ce building as modelled in IDA ICE 3.0 showing the simulated zones.
A detailed description of the geometry of the zones (including their number of repetition on each fl oor), the HVAC installations, the occupancy, the equipment, the artifi cial lighting and the furniture is given in Appendix D.
• Cell type offi ce layout
The fl oor area of the cell type offi ce building as defi ned in IDA ICE 3.0 (excluding the fan room) is 6177 m2. However, the non-residential space is 5448m2. In Figure 5.4 the area of each zone type is shown.
Figure 5.4 Zone areas for cell type offi ce building (p=persons).
As shown in Figure 5.4, 44% of the building area is corridor, 51% offi ce space and only 4% meeting rooms. Figures 5.5 and 5.6 show the fl oor plans for the cell type offi ce building (ground fl oor and 1st-5th fl oors).
Figure 5.5 Ground fl oor (cell type): Input for IDA ICE 3.0.
1 2 3 4
5 7 6
8
10 11
9
Figure 5.6 First - fi fth fl oors (cell type): Input for IDA ICE 3.0.
• Open plan offi ce
Figure 5.7 shows the area of each zone type.
Figure 5.7 Zone areas for open plan type offi ce building.
In the same way, 3 fl oors were also considered for the open plan reference building. The fi rst fl oor has 6 zones. There is airfl ow exchange between the zones 1, 4, 8 assuming a big opening (always open door) between them.
The ground fl oor is shown in Figure 5.8 and fl oors 1 to 5 in Figure 5.9.
1 2 3 4
5 6 8 7
10 11
9
Figure 5.8 Ground fl oor (open plan type): Input for IDA ICE 3.0.
Figure 5.9 First - fi fth fl oors (open plan type): Input for IDA ICE 3.0.
5.1.3 Description of building elements
• Thermal transmittance of the building materials
A description is given below of the properties of the building elements used for the reference building (see Table 5.1).
1
2
4 5
8 9
1
2
4 5
8
Table 5.1 Description of the building elements used, disregarding thermal bridges.
Building Material type Thickness Thermal Density Specifi c U-value element (from inside (m) conductivity (kgm-3) heat (Wm-2K-1)
Linoleum Linoleum 0.0025 0.156 1200 1260
fl oor Concrete 0.3 1.7 2300 880 1.75
The thermal transmittance of the materials used was initially calculated by IDA ICE 3.0. However, since the thermal losses due to thermal bridges were not included in these calculations, further calculations were carried out as described in Appendix E. A comparison between the theoretical values and the practical values calculated by Swedish Building Regulations is shown in Table 5.2. Finally, it was decided that the use of the practical values, according to the calculation procedure in the Building Regulations, was preferable for the simulation of the reference building. In order to meet the requirements of the Swedish Building Regulations (overall thermal transmittance of the building), modifi cations were made in the IDA ICE 3.0 library (increase of insulation for the external walls and roof ).
Table 5.2. Theoretical and applied thermal transmittance of the materials used.
Building element Theoretical U-value Applied U-value (Wm-2K-1) (Wm-2K-1) External wall (long façade) 0.27 0.32 External wall (short façade) 0.22 0.25
Internal walls 0.62 0.62
Roof (above 6th fl oor) 0.16 0.19
Ground fl oor 0.32 0.32
Intermediate fl oors 1.75 1.75
The total U · A value of the building envelope does not quite meet the requirements of the Swedish Building Regulations, but the energy use for heating meets the requirements of the Building Regulations reference building.
• Windows
A description of the geometry and the properties of the windows of the reference building follows.
o Windows of the long façade (type A)
sash frame
100mm 1.3 m
1 m
Figure 5.10 Typical window in the long façade.
Table 5.3 Properties of window in the long facade.
Window properties Size of window 1.3 m2 Uwindow typical of 90s 2 W/m2K
Glazing properties Description Triple glazed unit. Outer 4mm
clear fl oat, 30mm space, D4-12
inner IGU (Insulated Glazing
Unit).
Size (Ag) 0.88 m2
Ug (Calculated with Parasol) 1.85 W/m2K
Frame properties Description Wood covered by aluminium on the outside
Size (Ag) 0.42 m2 (32% of the total
window area)
Uf 2.31 W/m2K
Shading device* Description Intermediate white venetian blind placed in the 30 mm gap (at 45 degrees)
Uglazing effective 1.65 W/m2K
* Shading device: it is assumed that the venetian blind closes (100%), when the in-cident light inside the glass exceeds 100W/m2. The Uglazing effective was calculated by the Parasol software.
o Windows in the short façade (type B)
sash frame
100mm 2.7 m
1.6 m
Figure 5.11 Typical window in the short façade.
Table 5.4 Properties of window in the short facade.
Window properties Size of window 4.32 m2 Uwindow typical of 90s 1.94 W/m2K
Glazing properties Description Triple glazed unit. Outer 4mm
clear fl oat, 30mm space, D4-12
inner IGU (Insulated Glazing
Unit).
Size (Ag) 3.5 m2
Ug (Calculated with Parasol) 1.85 W/m2K
Frame properties Description Wood covered by aluminium on the outside
Size (Ag) 0.82 m2 (19% of the total
window area)
Uf 2.31 W/m2K
Shading device* Description Intermediate white venetian blind placed in the 30 mm gap (at 45 degrees)
Uglazing effective 1.65 W/m2K
* Shading device: it is assumed that the venetian blind closes (100%), when the in-cident light inside the glass exceeds 100W/m2. The Uglazing effective was calculated by the Parasol software.