Design Challenges in Courthouses

Transcription

1 Design Challenges in Courthouses Presented by Boggarm S. Setty, P.E. Setty & Associates, Ltd. ASHRAE Winter Meeting, New York, January 2008

2 Engineering Challenges State-of-the-Art New Architectural Trends Atriums Natural Ventilation Curtain Wall Systems Engineers Challenge in Designing HVAC Excellence Systems State-of-the-Art Technologies Energy Targets

3 State-of-the-Art Architectural Trends Atriums Curtain Wall and Double Systems Green Facades Underfloor Air Distribution Natural Ventilation and Operable Windows Historical Buildings

4 Architectural Trends: Atriums 300 foot tall Atrium Two levels to 30 levels South Facing Glass Enclosure Interior Atriums Construction Cost Usage

5 Architectural Trends: Double Wall and Curtain Wall Systems Double Glazing Floor-to-Ceiling Glass Mullions at Every 20 Feet Thermal Breaks Connections to Structural Systems

6 Architectural Trends: Double Wall and Curtain Wall Systems

7 Architectural Trends: Underfloor Air Distribution Courtrooms Entire Courthouse Special Areas such as Libraries Entry Areas Retrofit Areas Cost Comfort Condition

8 Architectural Trends: Underfloor Air Distribution

9 Architectural Trends: Historical Courthouses Air Distributing Challenges with Ceiling Structure Type Perimeter Heating and Cooling

10 Engineering Challenges: Atriums Conventional Cooling Dependent upon size of Atrium, cooling tonnage varies from 200 tons to 1,000 tons. Evaporative Cooling Does it really provide the necessary cooling for comfort or does it create more issues for maintenance? Cost Prohibitive Systems Can we prevent condensation? Designing Low Maintenance Systems

11 Engineering Challenges: Atriums Induction Cooling Vaporizing water and creating induction effect to bring outside air into the Atrium Does it really work? Creates Filtration Issues Frequent Atrium Glass Cleaning Excessive use of Water Return Air Cooling Have we really changed cooling and heating load characteristics? Bringing Air back to Cooling Coil

12 Engineering Challenges: Atriums Treatment of Circular Atriums High Energy Consumption Initial and Operation Cost Duct Distribution

13 Engineering Challenges: Underfloor Systems Design, Operational and Maintenance Issues Dewpoint Control in Underfloor Air Distribution System: Can we really control it without reheat? Perimeter Heating and Cooling: Can we really provide heating/cooling without perimeter system? Controls: Can we really provide individual controls for the spaces using this type of system?

14 Engineering Challenges: Underfloor Systems Design, Operational and Maintenance Issues Condensation: Can we really control condensation in the plenum space? Air Leakage: Leakage seems to be as high at 120% to 130% after Underfloor System is built and tested. Dust Control: Filtration of accumulated dust in the plenum space is not easy. Thermal Loss: Thermal loss in the slab below the floor.

15 Engineering Challenges: Natural Ventilation Design, Operational and Maintenance Issues Operable Windows with Sophisticated Controls: Each point to be monitored and possibly controlled. Control Devices: Maintenance issues of the operating devices. Acoustical Issues: Do we really provide an environment conducive for working when windows are open? Internal Air Quality: Do we really control the dust coming from the operable windows? Condensation: Can we really control condensation that may happen due to unconditioned air coming from the natural ventilation air? Can we really maintain temperature and humidity in the space?

16 Engineering Challenges: Double and Curtain Wall System Design Issues Heat Island: Heat island effects created between glazing. Outside Air: Outside air passing between the glass causes condensation issues and control issues. Glare: Controlling the glare created by east and west glass exposures. Thermal Breaks: Thermal breaks and condensation control.

17 Engineering Challenges: Double and Curtain Wall System

18 Engineering Challenges: Double and Curtain Wall System Design Issues HVAC Loads: Increase in heating/cooling loads. Energy: Increase in energy consumption. Pressurization: Pressurization is required to control condensation. Air Leakage: Air leakage at a ratio of.1 to 2.5 cfm/sq ft of glass area, creates heavy infiltration loads.

19 Engineering Challenges: Double and Curtain Wall System Design Issues Beam Connections: Heat transfer and condensation issues are at the beam connection with the spandrel.

20 Engineering Challenges: Energy Targets Conventional Buildings: 75,000 BTU/sq ft/year through 150,000 BTU/sq ft/year Projected Energy Consumption: for Courthouses 55,000 BTU/sq ft/year Can we really model the Atriums with specialized systems, such as induction cooling, evaporative cooling, return air path heating/cooling; or shall we manipulate the numbers? Can we really calculate the credits given by the natural ventilation system? Do we have a energy penalty or energy savings? Underfloor Air Distribution Systems: Can it really save energy? Courthouses are consuming 2 to 3 times more energy than predicted.

21 CONCLUSION Questions that remain to be answered Can we really provide comfort conditions with new Architectural trends? At what cost? Can we really save energy within new trends in Courthouses? These challenges face us in a changing world demanding reduced energy consumption.

22 Questions and Answers