pae consulting engineers, inc. Nick Collins, P.E., LEED™ AP Mechanical Systems pae consulting engineers, inc. Nick Collins, P.E., LEED™ AP nickc@pae-engineers.com inspire interpret integrate

? Mechanical Systems What kind of mechanical system?

Mechanical Systems Install the smallest, most efficient system possible: Reduce perimeter loads through careful skin design. Reduce internal loads: laptops, energy star equipment. Multnomah County Hillsdale Library Architect: Thomas Hacker and Associates

What Factors Determine the Mechanical System Selected? Building Type Office Housing Education, Higher Ed or Secondary Industrial Maintenance Comfort Mark O. Hatfield US Courthouse Architect: BOORA Architects Sokol Blosser Wine Barrel Storage Facility Architect: SERA Architects

ASHRAE summer and winter comfort zones.

Mechanical Systems Passive vs. Active PAE Offices

Active Systems Cooling Heating Air Distribution COOLING Direct Expansion Packaged Rooftop Chilled Water Air Cooled Water Cooled Central Ground Water Direct and Indirect Evaporative Cooling Distributed Heat Pumps Active Systems Cooling Heating Air Distribution HEATING Hydronic Conventional Hot Water Boilers High Efficiency Hot Water Boilers (Gas) Electric Heat Gas Fired Ground Coupled Heat Pump   AIR HANDLING Central Rooftop Penthouse or Inside Distributed Air Handling Fan Coils Unit Ventilators Heat Pumps

Active Cooling Systems Direct expansion Chilled water - Air cooled - Water cooled - Ground Water Direct and indirect evaporative cooling Distributed heat pumps

Cooling Systems Chilled Water Package Rooftop First Cost: Lowest potential first cost. Energy Cost: Higher energy cost. Maintenance: High maintenance costs - expected life of 15 years. Comfort: Reasonable – potential acoustical issues. University of Oregon School of Music & Dance Architect: BOORA Architects

Cooling Systems Chilled Water Air Cooled First Cost: In conjunction with air handlers. Energy Cost: Better than rooftop option. Maintenance: Lowest maintenance cost option - average life of 17 years. Comfort: High level of comfort.

Cooling Systems Water Cooled First Cost: Greatest first cost. Energy Cost: Lowest Energy cost. Maintenance: Equipment is highly reliable - chiller life is 27 years. Comfort: Provides the best in comfort - quiet operation.

Ground Source Heat Pumps GS heat pumps extract geothermal energy to condition buildings. Very low energy consumption. Winter – moves heat from the earth to the building Summer – moves heat from the building to the earth Automatic controls are used to reverse the direction of the heat transfer

Ground Water PSU Northwest Center for Engineering, Science and Technology. Ground water well system with extraction and insertion wells. No Boiler or Cooling Tower Ground water is used for heating and cooling.

Heating Systems Active Systems – Heating Hydronic - Hot water boiler - High efficiency boiler - condensing Electric heat Gas fired

Heating Systems Hydronic Heating Systems Energy Cost: Mid range, between electric heat and high efficiency hot water. Maintenance: Requires little maintenance. Comfort: Excellent comfort.

Radiant Floor Heating Consistent heating Low energy usage Slow response time

Heating Systems Electric Heat First Cost: Low first cost. Energy Cost: Very high. This will represent a 100% to 150% increase in energy cost due to rate differences between gas and electric. Maintenance: Low maintenance. Comfort:Step control on electric heaters. Acceptable comfort.

Active Systems – Air Handling Central Distributed - Fan Coils - Unit Vents - Heat Pumps

Air Handling Package Air Handler Variable Air Volume Air Handler Distribution: Conventional overhead Underfloor Lower energy savings - longer economizer cycle Smaller cooling zone

Air Handling Systems Heat Recovery Energy cost: Low energy cost. Maintenance: Same as air handler. Comfort: Less than air handler, if provided without coils.

Natural Ventilation Passive Cooling PAE Offices

Advantages of Natural Ventilation Simple Lower first cost (15% less) Lower operating cost (40% less) User satisfaction through greater control Elimination of mechanical refrigeration Less environment impact No mechanical noise

Advantages of Natural Ventilation Option A Simple Lower first cost (15% less) Lower operating cost (40% less) User satisfaction thru greater control Elimination of mechanical refrigeration Less environment impact No mechanical noise inspire interpret integrate

Disadvantages of Natural Ventilation Temperature & humidity cannot be tightly controlled No filtration Reduced security First cost higher if back-up A/C system is also required Exterior noise can be a problem Less flexible air intake locations – air quality issues Large openings required with mass inspire interpret integrate

Disadvantages Temperature and humidity cannot be tightly controlled No filtration Reduced security First cost higher if back-up A/C system is also required Exterior noise can be a problem Less flexible air intake locations – air quality issues Rain

Strategies Single-sided opening ventilation Cross ventilation Stack-induced flows through double opening

Washington School for the Deaf Classroom Natural Ventilation Daylighting Thermal Mass Night Flush No Filtration

Thermal Mass / Night Ventilation Need approximately 2 to 3 times the floor area Can reduce maximum daytime temperature

Sustainable Design Mechanical Systems What system? That depends . . . Reduce loads to lowest possible amount Know your client, maintenance, comfort, operating schedule, etc. Select most efficient system possible System Types - Active - Passive - Mixed Mode

Shattuck Hall – Case Study Existing Mechanical Systems Two dedicated outside air units with steam heat, evaporative air cleaners Multiple air zones with mix dampers Gravity relief from each zone (open relief duct on roof) Other smaller mechanical systems. pae consulting engineers, inc. inspire interpret integrate

Existing Classroom inspire interpret integrate

Old Zone Dampers - Mixing inspire interpret integrate

Mechanical Systems Options HVAC Option C – Conventional VAV Hot water heating Variable volume AHU’s Medium pressure supply ductwork VAV air terminal units in each space Low pressure return ductwork Return air plenums   HVAC Option D – Dedicated OA/Radiant Hot water heating radiant panels Fan-induced ventilation Operable windows – manual New AHU’s/Existing ductwork - for minimum outside air Radiant Cooling – radiant cooling panels or chilled beams HVAC Option A – “Natural” Ventilation Hot water heating radiators Operable windows – automatic, with trickle vents Building Mass/Night Flush Cooling   HVAC Option B – “Natural” Ventilation/Mixed Mode Fan-induced ventilation Operable windows automatic New AHU’s/Existing Ductwork Cooling coils in new AHU’s deliver cold air through existing ductwork on extremely hot days   pae consulting engineers, inc. inspire interpret integrate

Shattuck Hall New Mechanical Systems Two dedicated outside air units with hot water heating, campus chilled water and filters Temperature zones with VAV terminal units Radiant heating and cooling panels Gravity relief from each zone (open relief duct on roof) Other smaller mechanical systems. pae consulting engineers, inc. inspire interpret integrate

Estimated Energy Usage Energy Use in Shattuck Hall Estimated Energy Usage No envelope upgrades inspire interpret integrate

Radiant Panel Concerns Guinea Pig or Innovative Comfort Noise Condensate Valve locations Hot water leaks Flexibility inspire interpret integrate

Radiant Panels and Valves inspire interpret integrate

Heat inspire interpret integrate

Radiant Ceiling Heating / Cooling Dedicated outside air for dehumidification Low mass means faster response time Uniform heating and cooling Low energy usage inspire interpret integrate