Glass wool at 250 °C — heat-loss table

λ = 0.050 W/m·K at mean temperature ((250+20)/2 = 135 °C, from the published curve). Pipe losses per metre, four thicknesses, savings vs bare.

Pipe	30 mm W/m	50 mm W/m	80 mm W/m	100 mm W/m	BARE W/m	Surface @50 mm	Saving €/m·yr @50 mm	t CO2/m·yr
DN25	63	49	40	36	241	32 °C	€94	0.34
DN50	93	69	53	48	436	34 °C	€179	0.65
DN80	123	89	67	59	642	35 °C	€270	0.99
DN100	150	106	79	69	826	36 °C	€351	1.28
DN150	206	142	103	88	1,216	37 °C	€524	1.92
DN200	258	176	125	107	1,583	38 °C	€686	2.51
DN300	366	245	170	143	2,340	38 °C	€1,022	3.74

Assumptions: 20 °C ambient, still air (h=10 W/m²·K combined), €0.05/kWh fuel, 8000 h/yr, 82% efficiency, 0.183 kg CO2e/kWh (DESNZ 2024). Flat surfaces at this duty: bare 2,300 W/m² → 208 W/m² at 50 mm (≈€1,021/m²·yr saved). Method: ASTM C680 simplified — methodology. Your exact case: free calculator.

Context

All materials at 250 °C

Material	λ W/m·K	Loss W/m	Surface	Saving €/m·yr	t CO2/m·yr
Stone wool (mineral wool)	0.052	112	37 °C	€348	1.3
Glass wool	0.050	106	36 °C	€351	1.3
Ceramic fibre (RCF / AES blanket)	0.060	127	39 °C	€341	1.2
Aerogel blanket	0.027	61	29 °C	€373	1.4
Calcium silicate	0.067	139	41 °C	€335	1.2
Expanded perlite	0.070	145	42 °C	€332	1.2
Cellular glass	0.058	122	38 °C	€343	1.3
Microporous (fumed-silica) panels	0.023	50	27 °C	€378	1.4
E-glass needle mat	0.050	106	36 °C	€351	1.3
Silica needle mat / fabric	0.055	117	37 °C	€346	1.3

DN100 pipe at 250 °C, 50 mm insulation, per metre of pipe; bare loss 826 W/m. λ at mean temperature; € and CO2 per metre·year at €0.05/kWh, 8000 h, 82% efficiency. Method: ASTM C680 simplified (h=10).

Material datasheet: Glass wool → · temperature class: by temperature →

FAQ

Questions on this topic

How much heat does a pipe at 250 °C lose with glass wool?

With 50 mm at 250 °C (λ=0.050 at mean): DN50 loses 69 W/m, DN100 106 W/m, DN200 176 W/m — vs 826 W/m bare for DN100. Full table on this page.

What surface temperature does glass wool give at 250 °C?

≈36 °C with 50 mm on DN100 (20 °C ambient, still air). Personnel-protection targets (≤45–60 °C) may need more thickness — see the 80/100 mm columns.