Three lives for the same asset

Distribution and air-conditioning equipment → Heating and ventilation equipment → Chillers المبردات

English name: Projects Advisors translation.

The accounting life, as published: 15 to 25 years

26,667 a year at 15 years, 16,000 at 25

A difference of 10,667 a year, every year, on one asset. The short end is 67% higher and both are inside what the manual permits. Capitalisation threshold 10,000 SAR. The manual also prints a default life of 25 years. Comprehensive manual for the census and valuation of assets of government entities, Second edition, approved 10 September 2022; Ministry-hosted rendering, section 5.2, pages 78 to 152, page 90.

The observed service life

Chiller, centrifugal: replaced at a mean of 25.2 years, from 30 units, standard deviation 7.6, range 7 to 42209 units still running at a mean age of 17.6 years, which is a lower bound and not a life. Averaging all of them together gives 18.6, which is 26.4% below the observed figure. Why the two columns are never averaged.The largest replaced sample in the cooling set, and still only 30 units. The standard deviation of 7.6 on a mean of 25.2 is a coefficient of variation of 30%, and the observed range runs from 7 to 42 years.

Chiller, air-cooled reciprocating: replaced at a mean of 11 years, from 1 unit15 units still running at a mean age of 24 years, which is a lower bound and not a life. Too few replacements to compare against, so no percentage is offered here. Why the two columns are never averaged.One replacement. The figure is an observation, not an estimate, and the in-service mean of 24.0 across 15 units is the more informative number here even though it is a lower bound.

Chiller, air-cooled rotary (screw): replaced at a mean of 23 years, from 1 unit8 units still running at a mean age of 12.3 years, which is a lower bound and not a life. Too few replacements to compare against, so no percentage is offered here. Why the two columns are never averaged.A standard deviation of 10.3 on a mean age of 12.3 across 8 units in service. Nothing here supports a default.

Chiller, water-cooled reciprocating: no replacements reported9 units still running at a mean age of 20.6 years, which is a lower bound and not a life. Why the two columns are never averaged.No replacements reported. Every unit in the sample is still running at a mean age of 20.6 years, which is a lower bound and nothing else.

Chiller, water-cooled rotary (screw): no replacements reported5 units still running at a mean age of 11 years, which is a lower bound and not a life. Why the two columns are never averaged.Five units, none replaced.

Same machine under both names: a packaged water chiller serving a building. ASHRAE splits it by compressor and condenser type, which the ministry does not, so the accounting class covers all five rows. ASHRAE Service Life and Maintenance Cost Database, 345 buildings and 38,946 pieces of equipment, read 3 September 2026.

The design life

Yours to supply, because nobody publishes one. A design life belongs to a particular specification and comes from the design basis or the manufacturer. Its absence from every published table is the reason it is the life most often quoted and least often checked.