Using the AEDG in large hospitals


Graphics packages

  • Graphics are required for operator use and understanding of system performance. The adage “a picture is worth a thousand words” could never be more applicable in this case
  • Consolidating related system performance information on graphic screens enhance operator understanding of where energy is used, and what is setting the requirement for increasing the output of plant equipment. 

Exhaust air

  • Figure 3: In this mixed-air section configuration, use of dual (opposing) outside air entrances with air blenders (in cold climates) to eliminate stratification and minimize the use of preheat coils. Courtesy: Engineering Economics Inc.Less exhaust air can be achieved through better kitchen layouts with smaller kitchen hoods, no isolation exhaust when isolation rooms are not in use, and separate AHU exhaust air damper control.
  • Less exhaust requires less minimum outside air, less heating, and less cooling, with the more significant benefits to be obtained in high humidity areas where dehumidification requirements are prevalent.
  • Closer compliance with actual requirements, in lieu of adding a little extra to make sure. To this end, we highly recommend larger variable speed drive exhaust fans with static pressure control, in lieu of fixed speed, constant volume exhaust fans. Exhaust air requirements can be more accurately balanced, and quantities are ensured by varying fan speeds to exactly what is needed at the inlet grills, not just a proportional balance of fixed exhaust air quantities. 


  • Less fittings, less devices
  • Wyes in lieu of tees
  • Full port ball or butterfly valves
  • Two-way valves, more diversity. 


  • Less humidification—this is often overdone, and not required or desired. Refer to local codes to determine the amount of relative humidity required in the winter.
  • Smaller zones versus entire AHU applications.
  • Better control, and shutoff when not required. 


  • Less intake of humid outside air
  • Desiccant wheels in lieu of sub-cooling
  • Heat recovery. 

Heat recovery

  • Heat recovery is usually disappointing—extra air side static pressure losses, contamination of heat transfer surfaces, performance short of expectations, and/or no demand for recovered heat (hospitals really need more cooling or cooling enhancement in very hot or humid climates).
  • If exhaust air streams are minimized (the first step), the impact is either too small or too contaminated to justify heat recovery. The goal is to minimize exhaust air and then apply heat recovery, if at all.
  • Heat recovery can only be justified in very cold or very hot climates. Mild weather locations, or where the total number of hours when heat recovery will actually pay, may be limited in comparison to the total number of operating hours. 


  • Right-sizing of domestic hot water heating—the requirements are much less than the number of fixtures in a hospital would lead one to believe. A hospital has many fixtures, but few are used.
  • No booster pumps. Excessive use of booster pumps has been a major issue for lower multi-story buildings.
  • Centralized domestic hot water recirculation and balancing of recirculation loops. Better flow, less waste at the faucet.
  • Mixing valves with good check valves. Integral check valves have been less than satisfactory more often than not, with excessive hot and cold domestic water use to compensate. 

Building envelope

The building envelope and orientation of the building have significant impact on HVAC design, comfort, and operating practices. The orientation of large hospitals on the site is more often limited by the available site, parking, and other factors. However, the building envelope can be optimized by:

  • Eliminating thermal bridging. Continuous wall insulation between the structure and the exterior skin, and window frames, and more specifically, window sills must be thermally broken.
  • Providing a complete vapor barrier, with emphasis on the integrity of window and door openings, and the junctions of the wall assemblies with the floors and roof assemblies.
  • Less glass and better shading.
  • Exterior doors that limit infiltration. 


  • Less lighting, better located. General, overhead lighting versus task lighting has been a continual battle.
  • More efficient fixtures and lamps. Fewer watts, more lumens per watt, and better light quality to enhance medical diagnostic procedures.
  • Lighting controls, so lights are off when not needed. This has been challenging, with the lack of light when needed. Occupancy sensors do not always sense occupancy, particularly if there is little motion in the room. The approach may be some combination of daylighting, motion sensors, time of day control, or local switching in smaller zones.

No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2013 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
The true cost of lubrication: Three keys to consider when evaluating oils; Plant Engineering Lubrication Guide; 11 ways to protect bearing assets; Is lubrication part of your KPIs?
Contract maintenance: 5 ways to keep things humming while keeping an eye on costs; Pneumatic systems; Energy monitoring; The sixth 'S' is safety
Transport your data: Supply chain information critical to operational excellence; High-voltage faults; Portable cooling; Safety automation isn't automatic
Case Study Database

Case Study Database

Get more exposure for your case study by uploading it to the Plant Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.

These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.

Click here to visit the Case Study Database and upload your case study.

Maintaining low data center PUE; Using eco mode in UPS systems; Commissioning electrical and power systems; Exploring dc power distribution alternatives
Synchronizing industrial Ethernet networks; Selecting protocol conversion gateways; Integrating HMIs with PLCs and PACs
Why manufacturers need to see energy in a different light: Current approaches to energy management yield quick savings, but leave plant managers searching for ways of improving on those early gains.

Annual Salary Survey

Participate in the 2013 Salary Survey

In a year when manufacturing continued to lead the economic rebound, it makes sense that plant manager bonuses rebounded. Plant Engineering’s annual Salary Survey shows both wages and bonuses rose in 2012 after a retreat the year before.

Average salary across all job titles for plant floor management rose 3.5% to $95,446, and bonus compensation jumped to $15,162, a 4.2% increase from the 2010 level and double the 2011 total, which showed a sharp drop in bonus.

2012 Salary Survey Analysis

2012 Salary Survey Results

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.