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Slohvac: An HVAC Savvy Sloan?. Nick Gayeski 4.427J – HVAC L. Glicksman, L. Norford. Outline. Building Design Building Basics Solar Shading Building Envelope Heating and Cooling Loads HVAC System Design Displacement Ventilation Natural Ventilation. S. Building Basics.
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Slohvac: An HVAC Savvy Sloan? Nick Gayeski 4.427J – HVAC L. Glicksman, L. Norford
Outline • Building Design • Building Basics • Solar Shading • Building Envelope • Heating and Cooling Loads • HVAC System Design • Displacement Ventilation • Natural Ventilation
S Building Basics • Faculty Clusters in Corner Buildings, Classrooms/Large Conference Rooms in Central Buildings • 230,000 GSF roughly satisfies Sloan and E60 space requirements • Long East-West Axis and Shading Minimize Direct Solar Gains • Atrium Provides Diffuse Daylight • Buoyancy-driven natural ventilation supplemented by wind-driven ventilation and solar chimneys 50’ 100’ S River
5’ 9’ Altitude > 58° Solar Shading 4.6’ 3’ 26.5° tilt Azimuth > 100° • South Overhang • Blocks Direct Sun from 10 to 2 solar time in mid-summer • East and West Shading • Block Direct Sun after 9 (East) and before 4 (West) solar time in mid-summer
Building Envelope Windows – Optimize Based on Orientation • Double-Skin Outside Vented Facade on East and West Reduce Solar Gains • Double-Pane, Argon Filled Windows Used Throughout • Low-e Windows on North Façade • Clear Windows on South Façade Walls – High Thermal Mass and Insulation • 6” Concrete • 8 cm of EPS Insulation • Gypsum Board
3rd Floor Design Heating and Cooling Cooling Design • Consumes 3,155 kWh on Peak Summer Day • Peak Load ~ 218 kW at 2 pm Heating Design • Consumes 3,150 kWh on Peak Winter Day • Peak Load ~ 182 kW at 10 am Both ~ 286 kWh/m^2-yr for 365 Consecutive Peak Days Peak Flow Rates • Summer at 2 pm - 23.5 m^3/s or 50,000 cfm • Winter at 10 am - 25.2 m^3/s or 53,500 cfm
Mixed-Mode System Mode 1: Buoyancy and Wind-Driven Natural Ventilation Mode 2: Displacement Ventilation Return Office Circulation/Support Office Supply S North-South Cross Section
Return Exhaust Outdoor Air F HC CC Supply Steam HWS DM DM SP HWR Condensate Converter CWS Zone T CWR VAV, All-Air Displacement Ventilation Uses campus steam and chilled water.
Natural Ventilation Season Heating required for T < 8°C Cooling required for T > 22° • May, June, September, October • Some of April, July, August and November • Accounting for Buoyancy Only! • Season Could be Extended: • Wind-driven ventilation • Use for Night-Cooling
Conclusions Benefits • Natural Ventilation Possible ~ 1/3 of the Year or More • Even at Peak Load, Building Performs Better than 300 kWh/m^2-yr • Atrium Provides Daylighting and Enjoyable Semi-Outdoor Space • Underfloor Distribution Used In Both Ventilation Modes Drawbacks • High Volumetric Flow Rates – Ducts Take up Space • Thermal Mass Outside of Insulation • More Reduction of Solar Gains Possible, Though May Sacrifice Daylighting • More Consideration May be Needed for HVAC Systems on Floors 5-10 (If Buoyancy is Not Enough)
