HEALTH AND SAFETY

HVAC Recommissioning

Building operators are looking for ways to cut their operating budget for the coming years. Building recommissioning is an effective way to cut energy costs while improving the indoor environment. Buildings have a natural tendency to drift away from energy efficiency. Recommissioning puts the building back on course. A study released in July of 2009 by Lawrence Berkeley National Laboratory shows that the median whole building energy savings for existing buildings from recommissioning is 16%. This represents a typical payback time of 1.1 years. 

Many programs in Minnesota exist to encourage efficiency improvements. Recommissioning in schools is allowed to be funded under Health and Safety at intervals of no less than five years. Xcel energy currently has a program that will pay up to 50% of the cost of recommissioning to a maximum of $15,000 for Xcel customers.  Minnesota has more rebate programs for energy efficiency than any state in the country. 

Since approximately 24% of a buildings electricity usage is due to fan and pump motors, the HVAC system is an excellent area to implement improvements. Many HVAC systems operate fans and pumps at a constant speed even though the load on them is often much lower than the peak that the systems were designed for. Retrofitting pumps and fans with variable frequency drives (VFD) is a popular method of improving efficiency of these systems. Reducing the average speed of a fan or pump by 50% would result in a 12.5% energy savings for that piece of equipment.

There are many other energy savings opportunities that are investigated through recommissioning such as improving boiler efficiency/controls, tune-up of terminal unit dampers and valves, lower condenser water temps/improved chiller sequencing, calibrate sensors, correct test and balance issues, optimize economizer operation, eliminate simultaneous heating and cooling, and scheduling equipment properly.  Recommissioning is an important part of a building’s overall maintenance plan.

Recommissioning also reduces the carbon footprint of the building. Protecting the environment through reductions in green house gas emissions has become a higher priority to many building owners. Due to the energy savings of the recommissioning process the associated reductions in greenhouse gas emissions come at a negative cost. The study by Lawrence Berkeley Nation Laboratory shows that the median cost of conserved carbon is -$110 per tonne. In other words the school is getting paid to cut carbon and protect the environment! There has never been a better time to start saving money through recommissioning.

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