Cellular glass Insulation — λ(T), Max Temperature, Computed Heat Loss

Honest assessment

Strengths, limits, verdict

Strengths: 100% closed-cell: zero water absorption — the definitive CUI and cryogenic answer; incompressible; non-combustible.

Limits: brittle (needs careful support); expensive; lambda mediocre at hot temperatures.

Verdict: Cold, cyclic and wet service: LNG, chilled water, underground — where water is the enemy, nothing else competes.

Thermal conductivity (typical published values)

Mean temperature	λ W/m·K
-50 °C	0.038
0 °C	0.041
50 °C	0.046
100 °C	0.052
200 °C	0.068

λ at mean temperature — rises with T because pore radiation grows with T³.

Computed performance · ASTM C680 simplified

Cellular glass on real pipe sizes

At 100 °C (λ=0.047 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	152	31	28 °C	€59	0.22
DN50	50 mm	152	23	25 °C	€63	0.23
DN50	100 mm	152	16	22 °C	€66	0.24
DN100	30 mm	287	50	29 °C	€116	0.42
DN100	50 mm	287	35	25 °C	€123	0.45
DN100	100 mm	287	23	22 °C	€129	0.47
DN200	30 mm	551	86	30 °C	€227	0.83
DN200	50 mm	551	59	26 °C	€240	0.88
DN200	100 mm	551	35	23 °C	€251	0.92

At 250 °C (λ=0.058 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	436	106	48 °C	€161	0.59
DN50	50 mm	436	79	36 °C	€174	0.64
DN50	100 mm	436	55	27 °C	€186	0.68
DN100	30 mm	826	171	51 °C	€320	1.17
DN100	50 mm	826	122	38 °C	€343	1.26
DN100	100 mm	826	79	28 °C	€364	1.33
DN200	30 mm	1,583	294	54 °C	€629	2.30
DN200	50 mm	1,583	202	40 °C	€674	2.47
DN200	100 mm	1,583	123	29 °C	€712	2.61

At 400 °C (λ=0.068 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	720	202	73 °C	€253	0.92
DN50	50 mm	720	153	50 °C	€277	1.01
DN50	100 mm	720	107	33 °C	€299	1.09
DN100	30 mm	1,365	325	79 °C	€507	1.86
DN100	50 mm	1,365	235	55 °C	€551	2.02
DN100	100 mm	1,365	154	36 °C	€591	2.16
DN200	30 mm	2,616	558	84 °C	€1,004	3.67
DN200	50 mm	2,616	388	59 °C	€1,087	3.98
DN200	100 mm	2,616	238	38 °C	€1,160	4.24

Assumptions: 20 °C ambient, still air (h=10 W/m²·K), €0.05/kWh fuel, 8000 h/yr, 82% boiler efficiency, 0.183 kg CO2e/kWh. Your numbers: free calculator.

Against the field

Same duty, all materials — DN100 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).

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FAQ

Questions on this topic

What is the thermal conductivity of cellular glass?

Typical published values: 0.038 W/m·K at -50 °C, 0.041 W/m·K at 0 °C, 0.046 W/m·K at 50 °C, 0.052 W/m·K at 100 °C, 0.068 W/m·K at 200 °C (mean temperature). λ rises with temperature — design with the mean-temperature value, not the ambient one.

What is the maximum temperature for cellular glass?

≈430 °C continuous service for typical grades (ASTM C552 · EN 14305). Product-specific limits vary — check the datasheet of the exact grade.

Where is cellular glass the right choice?

Cold, cyclic and wet service: LNG, chilled water, underground — where water is the enemy, nothing else competes.

Cellular glass — properties, λ(T) and computed performance