Continuous Optimization=>Retro-Commissioning

Tasks that are common to both Re-Commissioning and Retro-Commissioning an existing building were outlined under Services for Continuous Optimization. This section further defines the approach that we take to Retro-Commissioning an existing building. A definition of Retro-Commissioning is as follows:


Retro-Commissioning: ASHRAE Guideline 0-2005 Definition:

The commissioning process applied to an existing facility that was not previously commissioned. The same basic process needs to be followed from pre-design through occupancy, and operations to optimize the benefits of implementing the commissioning process philosophy and practice.

  • The Retro-Commissioning process differs from that of Re-Commissioning in that it identifies retrofit opportunity that requires capital expenditure. Any and all types of retrofit measures can be evaluated depending on the scope of the project which is usually predicated upon the budget available.


  • Energy retrofit opportunity is identified through the typical energy audit or facility assessment process. An energy audit includes estimates of the installed cost of construction including retrofit design and quantifies the energy and cost savings for a particular measure while a facility assessment includes only construction cost estimates and not energy and cost savings estimates.


  • Water conservation opportunity is identified through walk-through audits where measurements are taken of typical flows for water closets, lavatories and showers. Typical flow rates are multiplied by the number of each fixture type to get the total annual water consumption based upon occupant use schedules of the facility. Water efficient fixtures are identified and estimates of annual water consumption savings are developed.


  • Lighting retrofit opportunity is identified through lighting audits. These can be initially accomplished by reviewing as-built electrical lighting drawings followed up by a field survey that tests the accuracy of the as-builts. A more vigorous approach includes a detailed field survey that actually counts lamps, fixtures and ballasts.


  • Motor retrofit opportunity is identified through an audit of all the motors in the facility.


  • Compressed air retrofit opportunity is identified through a survey of all the compressed air system including air compressors and distribution system piping and pressures.


  • Measures that reduce maintenance costs and improve comfort but do not save much energy can also be identified.


  • A detailed report summarizing the findings and recommendations is developed and is used as a planning tool for budget preparation.


  • Once the budgetary process has been completed and the package of retrofit options have been selected, the process proceeds to the Retrofit Design stage.


HVAC Retrofit Design involves forensic engineering investigations where detailed field measurements of air and water flow and electrical measurement of motor loads are taken. Engineering design is based upon as-built conditions verified in the field. Plans and specifications are developed and put out to bid through the traditional bidding process.

Retro-Commissioning documentation is included in Divisions 1, 15 and 16 in the bidding documents.