Low-Cost Tweaks Yield Big-Time Savings

Once Jack Dale Associates (JDA) quantified mechanical-system interactions for Texaco's data center, specified techniques were employed to upgrade the plant while avoiding disruptions to data-processing operations. Total construction costs for chiller-plant renovations commissioned by JDA were less than $600,000.

Once Jack Dale Associates (JDA) quantified mechanical-system interactions for Texaco’s data center, specified techniques were employed to upgrade the plant while avoiding disruptions to data-processing operations. Total construction costs for chiller-plant renovations commissioned by JDA were less than $600,000.

Procedures outlined by the engineering team improved energy efficiency and continue to save the petrochemical company more than $100,000 per year in utility costs. The design not only solved operating problems, but also improved the facility’s ability to increase its chilled-water reserve for future expansions. Best of all, the upgrades reduced energy consumption. Key features include:

The upgrades help set system demand and to ensure that only the required amount of chilled water is distributed.

Before JDA began work on the project, Texaco had received a number of proposals for resolving the facility’s system problems. The least onerous of the proposals would have required a two-week shutdown of the entire 5,000-ton chiller plant and over $2 million to complete.

Table 1 – Existing HVAC System Parameters

TimeBypass positionB riser flowB supply tempB return tempMain CHW supply temp FChilled water flow (gpm)Flow to labs (gpm)BAX flow (gpm)East-West riser flow (gpm)Main return header pressure (psi)Main supply header pressure (psi)IBM CDU flow (L/M)

13:00	Closed	1584	44.6	52.7	43.6	2778	414	617	1610	66	65	190
13:15	10% open	1665	44.7	52.1	43.7	2787	426	626	1661	65	64	190
13:20	15% open	1634	44.6	52.1	43.6	2737	432	637	1655	65	65	190
13:30	20% open	1666	45.0	52.0	43.7	2645	505	636	1704	65	65	200
13:38	25% open	1686	45.0	52.1	43.9	2655	504	630	1713	65	66	200
13:43	35% open	1669	44.4	52.3	44.0	2635	504	637	1728	65	66	200
13:49	Full open	1662	44.6	52.7	44.3	2671	502	630	1778	66	67	200
13:57	Full open	1363	44.1	54.5	44.3	2631	513	627	1864	68	68	145
14:08	Full open	1333	43.5	54.1	43.8	2611	517	635	930	69	70	130

Table 2 – Savings from Mechanical Plant Re-engineering

Original designRe-engineered design

	HP	kW		HP	kW
Subtotal:	972	611	Subtotal:	223	118
Chiller loads:	2,200	1,760	Chiller loads:	1,600	1,280
Total HP & kW:	3,172	2,371	Total HP & kW:	1,832	1,398
Dead head factor:		0.90	Pump kW saved:		973
Total kW Demand:		2,134 kW	Total kW demand:		1,398
Use factor:		0.80	Use factor:		0.80
Annual pump utility cost:		$235,462	Annual pump utility cost:		$45,530
			Added utility cost for new office space:		$79,684
			Net annual utility savings after chiller plant renovations:		$110,248

Average cost per kWh: 0.055 $/kWh