An HVAC Audit of the Canberra Institute of Technology 30 th November 2016 Amnon Holland amnon.holland@esbsconsult.com.au www.esbsconsult.com.au
Agenda Overview CIT and various other sites The sites Type of Buildings HVAC Audit typical scope Examples of Common Technical issues and opportunities (Controls, Operations & State of commissioning) Note: Behavioural/ Management is important but not covered. E.g. Set points, proactively changing time schedule to suit space use. BMS Diagnostics
HVAC Audit Typical Scope 1. Use metering data or other means to establish energy use breakdown 2. Walk through site inspection by Engineer, taking measurements (air/waterflow, temperature, pressure, power, etc) as necessary. 3. Review of most recent Air, Water and System commissioning results 4. Review of BMS trend data to understand controls opportunities
HVAC Audit kwh Load reduction (E.g. OA and infiltration reduction, Capacity control Airflows/Waterflows State of tuning Time Schedules OSS Zoning Afterhours
BMS Start/Stop Public holidays are often not programmed 10 days/p.a. = 3%/p.a. Energy Time schedules are often advanced by a few hours for warmup (especially in Canberra), due to occupant complaints. This indicates malfunctioning OSS or other issues. (Which need investigation!) The OSS software does not have a runout limit and a 3am start may occur. Teaching spaces All areas often left conditioned 24/7 despite only < 20% occupancy due to resource constraints (i.e. FM doesn t have time) Integration of room booking systems with BMS?
Airside Fans and Motors Fan pressure setpoints are excessive, not having been based on commissioning data. Also no dynamic pressure reset for VAV systems Fans are often running at low speed on the end of their turndown(10hz) and require a pulley change. (Since they have been oversized) Fans are throttled by poor balancing or by decommissioned inlet guide vanes.
Airside Fans and Motors All too common scenario Electrician installs VFD, everyone expects savings will result Reality VFD was left at 50Hz Inlet guide vanes not opened Fan used more energy than before due to lack of commissioning Throttling, Speed control
Airside - VAVs Electric reheats operating during warmup Dampers and airflow sensor mechanical issues (Easily picked with diagnostics) Not sequenced to use gas heating(ahu HW coils) before electric reheat (or lack the smarts to do so) Reduce reliance on series fan assisted boxes (Often not required if system is rebalanced) Poor control zone definition such as high select Minimum airflow setpoints and Ventilation rates = Opportunities for significant energy savings (from fan energy, chiller and boiler) Minimum outdoor air strategies Often unreliable Excess OA rates
Waterside Installation of VFDs without recommissioning Hydraulic issues including poor connection locations: Parallel boilers/chillers not receiving common return water temp and unable to load equally Flow circulation through non operating equipment causing casing losses. Constant Flow loops ->VF opportunities? Hardware probably already there, just recommission
Plant and Equipment Tenant CDW Loop is served by a base building pump and tower Common issues: Pumps running 24/7 or cycling to maintain low leaving conditions at low load Loops not balanced, resulting in much higher pumping power When equipment is added or subtracted the loop must be balanced. Has your tenant CDW loop been balanced?
Plant and Equipment Tenant CDW Oversized pumps (sized based on all tenants needing sup cooling) Possible solution - Since most are duty standby, replace one with smaller pump for better turndown
Plant and Equipment - Boilers Condensing boilers inefficient operation with return temp above 55 C 10% difference in gas consumption by dropping water temps <55 C Full load conditions vs actual. What about a 70/50 C design condition?? A BMS controlled boiler flow temp reset is necessary to gain the 10% efficiency over the year.
Standby Power Chillers - ~0.5-1kW continuous per compressor. Multiple chiller installations can switch off chillers and sump heaters. Generators Block heater loads can be substantial for medium to large generators Consult with manufacturer about lower temp thermostats. UV Sterilisation lamps Be mindful how long lamps are run for. Can lamps be inadvertently left on? Cooling tower dosing pumps These can usually be interlocked with Dosing controller for a signal to run rather than 24/7.
DHW Water Consumption Gas Consumption Circulation losses can be higher than use annually. The circulator ran 24/7 Sequencing issues with solar preheat/ connections in wrong location
Hours BMS Diagnostics BMS prerequisites (Talk to your BMS provider to setup): 1. Trends setup on all control or points of interest @15min intervals 2. Ability to download time aligned data (12 months) into excel 3. Start trending data so it is available for review Targeted KPIs to overall system performance. Target specific zones out of hundreds of VAVs. Some examples 250 200 150 100 50 AHU 3 Number EDH operation hours before 8am EDHs Shouldn t operating during optimum start 0 G4 G5 G6 2.8 4.6 5.6 6.6 VAV
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 More Hours BMS Diagnostics 500 450 400 350 300 250 200 150 100 50 0 AHU 5 Duct Pressure 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 AHU-1 Annual Heating Setpoint Deviation 1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.2 5.1 5.2 6.1 6.2 Identify Problem zones with basic excel diagnostics
BMS Diagnostics Same problem zone as before AHU- 1 % time at minimum airflow setpoint AHU-1 % time at maximum airflow 80% 30% 70% 60% 50% 25% 20% 40% 15% 30% 20% 10% 10% 5% 0% 1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.2 5.1 5.2 6.1 6.2 0% 1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.2 5.1 5.2 6.1 6.2 Cooling Heating Heating Cooling VAV operating as a constant volume system due to conservative designers
Thank you Email me for simplified checklist amnon.holland@esbsconsult.com.au