Volume 27, number 3, December 2013

Recommissioning: Concrete examples and more than satisfactory results

Background

Renovating a building, commonly called “recommissioning” or “RCx,” is an energy savings strategy now well known in the energy market. Already, in 2010, an Informa-TECH article “Recommissioning… Re what”?¹ summarized the concepts and principal phases.

The benefits of RCx are many, both in terms of energy and operations, as well as in comfort. While it is known that the potential energy savings achieved can be between 5-15% of initial consumption, it is also true that the majority of projects can often surpass those percentages when it comes to natural gas savings. Given its very short payback period, the process becomes practically a “must do. ”However, many customers are still unaware of the benefits or do not know how to tackle such a project.

An approach oriented on planning and investigation

Specifically, RCx puts the emphasis on the process and the approach. The quality of the work of the professional given the mandate to plan the study and investigation of the systems is of vital importance to the success of the project since the fees of an RCx consultant can represent between 35-75% of the total costs of a project.² Throughout the detailed exercise, engineers and technicians carry out functional tests and in-depth reviews of the building’s needs, which go far beyond simple schedule revisions or an energy performance profile. The agreement with the customer must therefore explain this reality and the details of the tasks and systems affected by the project. For the customer, the result is a complete report, listing everything from the simplest to the most complex improvements and best practices for the building. Since new equipment will not necessarily be installed, the hand-off phase and the persistence strategies must also be carefully planned to ensure the benefits are long lasting.

Some statistics to consider³

Savings
  • Energy
$1.00 – $8.00/m²

5 – 15%

  • Non-energy
$1.00 – $4.75/m²
RCx costs $2.90/m² (averages, total)

35-75% of the costs relate to investigative work and professional fees

Planning: Clearly identify projects and potential

While RCx was conceived to alleviate energy consumption problems, great savings potential can also be found in some relatively recent buildings that are already efficient and well maintained. Optimizing the systems in place thus maximizes the use of existing systems, as is shown by the following examples.

McGill University
(Life Sciences Complex)

In 2012, McGill University began an ambitious recommissioning program for several of its buildings.This new initiative added to the many projects undertaken by McGill to reduce its environmental footprint and its energy costs while improving the quality of the indoor environment.

Among the projects under way, the one involving the Life Sciences Complex is already showing very promising results. Although built in 2007 and designed for high efficiency, the pavilions of this complex were experiencing growing energy consumption. This gave an internal team the idea of optimizing everything – of making the systems even better than when they were built.

A multi-disciplinary recommissioning team, formed fore most of the McGill team coupled with specialists from Bouthillette Parizeau, was thus established to find ways of making the installation more efficient. The results of this exercise are impressive: a targeted reduction in energy consumption of more than 20%, with a payback period of less than one year.

A rigorous methodology was thus adopted in order to carry out complete functional tests on all the systems. One of the measures discovered was so major that it was implemented right way. The exhaustive investigation showed that a series of optimizations could better exploit heat recovery from the coolers, which had never been able to achieve their full potential: the optimal adjustment of the systems’ temperature and pressure set-points, reparameterization of outlet temperatures to the condensers; and reprogramming of the transfer sequence between the various coolers. A major improvement was noted immediately after implementing the modifications: heat was no longer being expelled outdoors, the number of heating boilers in operation was drastically reduced, and there was a significant reduction in the consumption of natural gas. This measure alone led to sustained savings in the order of $100,000 per year.

In total, about a dozen measures are being implemented that will generate total savings of more than $170,000 per year! Proud of this result, McGill is now very enthusiastic about applying this same approach to its other buildings.

Summary of performance

Consumption (area = to 16,706 m2)
Total Electricity Natural gas
Existing 71,515 GJ
4.28 GJ/m2
13,223,584 kWh 630,690 m3
Improved 52,386 GJ
3.14 GJ/m2
11,858,562 kWh 255,880 m3
Savings 19,116 GJ
27%
1,365,022 kWh
10%
374,810 m3
>50%
Simple payback period, before grants4 0.45*

Concordia University (implementation in progress)

Pageau Morel et Associés carried out a recommissioning project on the mechanical systems in Concordia University’s Engineering and Visual Arts Complex. The complex, with two towers of 12 and 17 floors respectively, houses classrooms, offices, research laboratories and workshops, and is accessible 24/7.

Since its construction in 2005, the mechanical systems have been subject to rigorous maintenance and continuous optimization by the University. When faced with a new recommissioning project, Concordia’s expectations and objectives were well identified, as well as the principal problems related to the operation of the systems and the comfort of the occupants.

A recommissioning plan was thus drawn up, with particular attention paid to pressurizing the ground floor and optimizing energy recovery from the coolers – the primary source for the low temperature heating system, which is a significant issue for Concordia. A one-year study of the systems showed that a large majority of the equipment was operating optimally based on the installations in place.

In regard to pressurizing the ground floor, the existing controls systematically increase the supply of fresh air during cold periods. An overall view of the ventilation systems’ operation helped reduce air infiltration by combining the ground floor pressure controls with dynamic modifications to the fresh air supply to all the systems in the complex.

A second measure is aimed at increasing energy recovery. Optimizing the low temperature heating system through modifications to the piping helped increase the flow of water to be heated. A specific analysis of the system showed that simple reconfigurations could potentially increase the heat exchange by more than 50% by modifying the flow and the approach (∆T) at the existing exchanger!

Summary of performance

Consumption (area = 69,300 m2)
Total Electricity Natural gas
Existing 79,550 GJ
1.15 GJ/m2
19,870,000 kWh 216,500 m3
Improved 74,900 GJ
1.08 GJ/m2
19,790,000 kWh 99,400 m3
Savings 4,700 GJ
>5%
81,600 kWh 117,000 m3
>50%
Simple payback period, before financial assistance 5 3.5*

* As well as identifying some measures with a payback period of less than 3 years, the project helped focus on more important measures that were then integrated into the implementation plan.

Conclusion

The Recommissioning of Building Mechanical Systems is one of Gaz Métro’sfinancial assistance programs and isaimed at supporting thisapproach and financing such projects.

For more information, visit gazmetro.com/remiseaupoint.

Mathieu Rondeau, Eng., CEM, LEED GA®
DATECH Group

Article written in collaboration with:

Yan Ferron, Eng., M. Env.
Pageau Morel et Associés

Eddy Cloutier, Eng. PA LEED®
Bouthillette Parizeau

  1. BEAUCHEMIN, Marc. “Recommissioning… Re what?” Informa-TECH, Vol. 24, No.3, December 2010. Online: www.gazmetro.com/informa-tech
  2. CanmetENERGY, NATURAL RESOURCES CANADA. Recommissioning (RCx) Guide for Building Owners and Managers, 2008. Statistics from the Lawrence Berkeley National Laboratory.
  3. Ibid.
  4. Including estimated implementation and engineering costs divided by energy savings.
  5. Including estimated implementation and engineering costs divided by energy savings.