Thursday, 20 October 2016

Energy Savings

All occu­pied buildings have teams of people who know everything about how the building works, right? 

Wrong. There are likely to be only 1% of facil­ity managers who actually know their building’s energy systems in detail. Most people who work in the building are only interested in “Do the lights work?” and “Is anyone complaining?”

Facility teams are expected to be knowledge­able but 99% don’t pay close attention to energy; there are too many plugged toilets, leak­ing roofs, rooms that need cleaning, lights that need lamps, new offices to partition and a never ending list of other demands from the Building Occupiers. ASHRAE’s Procedures for Commercial Building Energy Audits is a thorough resource for the information needed to understand an existing building’s operation and at only $109 is a great place to start.

  • Do you have a leaking envelope due to poor exterior caulking or faulty HVAC dampers?
  • What about the toilet extract fans? Are they running 24/7, especially when the air han­dlers are off at night
  • Do you run the building HVAC system manu­ally, making changes based on temperatures, expected weather conditions, occupier complaints etc.?
  • How many air and water controls have been adjusted from the original design set point.
  • Do you have a new tenant who works 16 to 18 hours a day and uses equipment way over original design duty?

Many buildings (most, it seems) are giving minimal attention to mainte­nance. HVAC problems are often ignored until they become major, so it’s well worth the time to carefully inspect and assess the cur­rent operation.

If you haven’t considered that fact lately in the context of buildings, think about why you take your car in for a service or why you visit your doctor for a check-up or why you mow the grass, for that matter.

Buildings are no different, but somehow are perceived differently when it comes to ongoing maintenance.

Let’s face it the common “preventive maintenance” contract is a bare minimum scope of work with no time devoted to evalu­ation of performance apart from filter changes, bearing lubrication or equipment that’s obviously not working.

Energy saving ideas should be driven from the maintenance team upwards. Unfortunately, the people with most knowledge of the building have the least time to undertake this function due to the short change contract they are working to.

If you are interested in solving your energy usage then resist the pigeon hole method in which you start with your energy bill which is then distributed into smaller pigeon holes based on CIBSE values for the fans, pumps, light­ing, cooling, heating, floor power, domestic hot water, etc.

This approach has no pigeon hole to represent wasted energy, even though it could be as high as 30% of the total energy use.

Consider the following situations as examples of what you may be unaware of.

  • BMS incorrectly calibrated or working with old technology with little trending data.
  • Pipework is not insulated wasting both cooling and heating energy.
  • Valves have had their insulation removed but not replaced. 
  • Pump motors are not controlled correctly. A booster set will pump on demand no matter how low. This results in a 3-minute cycle and most of that time will be against a closed valve.
  • Lift shaft damper open creating a high velocity 24/7 chimney causing the core to cool rapidly and the HVAC to start early.
  • Check AHU economiser locations. Is it located on a south facing enclosure seeing 23°C in the sun when it is really 16°C, forcing all AHUs to minimum outdoor air and full me­chanical cooling.
  • Is the economiser changeover set point 13°C instead of 21°C?

If the site inspection is hurried or hampered by time and budget constraints then, you cannot evaluate the building in enough detail to understand operations.In a full 48 hour inspection of one building the engineer discovered:  

  • Pumps running 24/7 or not running at all.
  • Fan motore running but not driving fans. 
  • Booster sets running against closed valves.
  • Pneumatic controls faulty, fan coil motors failed and signals from economiser incorrect. 
  • Pipework, valves and ductowrk uninsulated. 
  • Strainers clogged. 
  • Chiller compressor failures
  • Filters clogged or missing 

Each one of these problems should have been picked up and actioned during a full site inspection or PPM walk around by the resident maintenance engineer. 
The building occupier’s method of curing heating and cooling problems was to install new AC units because the staff were complaining “Most people who work in the building are only interested in “Do the lights work?” and “Is anyone complaining?”  Short term solution to long term issues.

Following all of the repair and upgrade work the energy bill dropped by more than 25% and the money spent was recovered in less than two years. There was nothing glamorous about any of the work orders received and each one varied in cost and ROI but the overall result was reduced carbon footprint and happier staff. Apart from the resident maintenance engineer who now works in the post room.

It is a similar situation with the RABScreen external filters. Small value projects with high ROI and brilliant energy saving. If you don't know what a RABScreen is just click to find out more.  

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