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Abbey Community College
Wicklow

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U-Value Calculations

Year 1986
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
Outside surface resistance 0.070
Resistivity of Asphalt 1.200 0.02 0.024
Aerated concrete 4.100 0.080 0.328
Concrete 0.714 0.140 0.100
Plaster 2.180 0.013 0.028
Inside surface resistance 0.110
R total 0.660
U value= 1 = 1
R total 0.660
1.514 m² °C/W
Year 1986
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
Internal surface resistances 0.110
Plaster 2.2 0.013 0.029
Concrete block 0.715 0.220 0.157
Internal surface resistances 0.110
R total 0.406
U value= 1 = 1
R total 0.406
For 1 degree 2.464 W/m² °C
For 15 degrees 36.955 W/m²
Year 1988
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External surface resistance 0.053
Facing bricks 0.714 0.1
Cavity resistance 0.176
Aerated concrete block 4.545 0.1 0.455
Lightweight plaster 6.25 0.015 0.094
Expanded polystyrene 0.033 30.303 0.025 0.758
Plasterboard 0.016 62.5 0.013 0.794
Internal surface resistance 0.123
Ignore the timber battens.
R total 2.452
U value= 1 = 1
R total 2.452
0.408 W/m² °C
Year 1989
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External surface resistance of tiles 0.053
Concrete tiles 0.833 1.2005 0.020 0.024
Internal surface resistance of tiles   0.123
Gross loft space   0.176
Glass wool 0.033 30.303 0.1 3.030
Plasterboard 0.16 6.25 0.012 0.075
R total 3.481
U value= 1 = 1
R total 3.481
0.287 W/m² °C
Year 1990
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
Rso 0.053
Glass 1.022 0.9785 0.005 0.005
Rsi 0.123
R total 0.181
U value= 1 = 1
R total 0.181
For 1 degrees 5.528 W/m² °C
For 21 degrees 116.091 W/m²
Area 1.65 3.000 = 4.950
4.950 116.091 = 574.651 Watts
k r m (Meters) R
Rso 0.053
Glass 1.022 0.9785 0.005 0.005
Cavity 0.028 35.714 0.0127 0.454
Glass 1.022 0.9785 0.005 0.005
Rsi 0.123
R total 0.639
U value= 1 = 1
R total 0.639
For 1 degrees 1.564 W/m² °C
For 21 degrees 32.846 W/m²
Area 1.65 3.000 = 4.950
4.950 32.846 = 162.585 Watts
Year 1991
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External surface 0.05
Facing bricks 1.4 0.7143 0.1 0.071
Cavity 0.180
Aerated concrete blocks 0.22 4.5455 0.1 0.455
Lightweight plaster 0.16 6.25 0.015 0.094
Internal surface 0.12
R total 0.970
U value= 1 = 1
R total 0.970
1.031 W/m² °C
k r m (Meters) R
External surface 0.05
Facing bricks 1.4 0.7143 0.1 0.071
Cavity 0.180
Aerated concrete blocks 0.22 4.5455 0.1 0.455
Lightweight plaster 0.16 6.25 0.015 0.094
Foil backed plasterboard 0.48
Internal surface 0.12
R total 1.450
U value= 1 = 1
R total 1.450
0.690 W/m² °C
Year 1993
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External surface resistance 0.403
Asphalt resistivity 1.2 0.02 0.024
Lightweight concrete 1.96 0.070 0.137
Concrete slab resistivity 0.69 0.15 0.104
Plaster resistivity 2.17 0.015 0.033
Internal surface resistance 0.104
R total 0.804
U value= 1 = 1
R total 0.804
1.243 W/m² °C
Year 1995
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External surface 0.053
External rendering 2.000 0.02 0.04
Lightweight concrete block 4.550 0.10 0.455
Cavity insulation 28.570 0.05 1.4285
Dense concrete block 1.190 0.10 0.119
Internal plaster 6.250 0.02 0.09375
Internal surface 0.123
R total 2.312
U value= 1 = 1
R total 2.312
0.432 W/m² °C
Year 1996
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External Surface 0.053
Conductivity of render 0.480 2.083 0.019 0.040
Brick 0.084 11.905 0.100 1.190
Cavity 0.176
Concrete bloc 1.440 0.694 0.100 0.069
Conductivity of plaster 0.480 2.083 0.013 0.027
Internal Surface 0.123
R total 1.679
U value= 1 = 1
R total 1.679
0.596 W/m² °C
Year 1997
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
Internal surface resistance: 0.123
Plaster 0.5 2.000 0.020 0.040
Common brick 1.21 0.826 0.100 0.083
Cavity- resistance (R): 0.176
Facing brick 1.47 0.680 0.100 0.068
External surface resistance: 0.053
R total 0.543
U value= 1 = 1
R total 0.543
For 1 degree 1.843 W/m² °C
For 20 degree 36.855 W/m²
Year 1999
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
External Surface resistance 0.053
Facing brick 1.4 0.714 0.100 0.071
Cavity Resistance 0.176
Urethane Boards 0.033 30.303 0.035 1.061
Aerated concrete block 0.22 4.545 0.100 0.455
Lightweight Plaster 0.16 6.250 0.015 0.094
Internal Surface Resistance 0.123
R total 2.032
U value= 1 = 1
R total 2.032
0.492 W/m² °C
k r m (Meters) R
External Surface resistance 0.053
Facing brick 1.4 0.714 0.100 0.071
Cavity Resistance 0.176
Blown Fiber Insulation 35.714 0.035 1.250
Aerated concrete block 0.22 4.545 0.100 0.455
Lightweight Plaster 0.16 6.250 0.015 0.094
Internal Surface Resistance 0.123
R total 2.222
U value= 1 = 1
R total 2.222
0.450 W/m² °C
Difference Improved 0.042 W/m² °C
(reduces heat loss)
Year 2000
Element Conductivity Restivity Thickness Resistance
Symbol k r m (Meters) R
Rso 0.08
Glass 1.02 0.9804 0.005 0.005
Cavity 0.150
Glass 1.02 0.9804 0.005 0.005
Rsi 0.120
R total 0.360
U value= 1 = 1
R total 0.360
For 1 Degree (& 1m²) 2.779 W/m² °C
For 20 Degree(& 1m²) 55.586 W/m²
Area of glass 6.000
For area of glass 55.586 x 6.000
= 333.515 Watts