Modern HVAC-systems for nearly zero energy buildings

Modern HVAC-systems for nearly zero energy buildings Maija Virta M.Sc.(Eng.) Head of Operations, Santrupti engineers Fellow of REHVA,Member of ASHRAE Federation of European Heating, Ventilation and Air-conditioning Associations 1

Technologies Used in Zero Energy Buildings Reduced Energy Need Active and passive beams Chilled ceilings and TABS Radiant floor cooling (&heating) Displacement ventilation UFAD (under floor air diffusion) Natural and hybrid ventilation Night purge ventilation Personal ventilation Active solar shading LED lighting Light tubes (daylight) BMS Focus of this presentation is on underlined HVAC technologies Reduced System Energy Use DOAS Energy recovery Dehumidification Adiabatic & desiccant cooling Evaporative cooling Demand based ventilation Earth tubes Condensing boilers On-site Energy Production District heating and cooling Heat pumps Solar heat Solar cooling Photovoltaic (PV) Wind turbines Federation of European Heating, Ventilation and Air-conditioning Associations 2

Passive Chilled Beams Federation of European Heating, Ventilation and Air-conditioning Associations 3

Main Principles of Passive Chilled Beam Passive chilled beams comprise a heat exchanger for cooling, and when desired for heating. The operation is based on natural convection. The primary air is supplied to the space using separate diffusers either in the ceiling or wall, low velocity units at low level or alternatively through the raised floor. Federation of European Heating, Ventilation and Air-conditioning Associations 4

Active Chilled Beams Federation of European Heating, Ventilation and Air-conditioning Associations 5

Chilled Beam Operation 1. Primary air (dehumidificated outdoor air) supply into supply air chamber 5 1 2 4 3 2. Primary air is supplied through small nozzles. 3. Primary air supply induces room air to be re-circulated through the heat exchanger of the chilled beam. 4. Re-circulated room air and the primary air are mixed prior to diffusion in the space 6 5. Cold water connection 6. Warm water connection Federation of European Heating, Ventilation and Air-conditioning Associations 6

Chilled Beam Operation Exposed chilled beam for installations without suspended ceiling Closed chilled beam for installations with suspended ceiling Federation of European Heating, Ventilation and Air-conditioning Associations 7

Federation of European Heating, Ventilation and Air-conditioning Associations

Chilled Ceilings Federation of European Heating, Ventilation and Air-conditioning Associations 12

Total Cooling Capacity 19 O C 40 O C 37 O C 26 O C 26 O C Radiation: 5.5 W/m 2,K t operative = 25 O C, t surface = 19 O C, P radiation = 33 W/m 2 (dt=6k) 19 O C 26 O C 40 O C 37 O C 26 O C Natural Convection: P convection = 65 33 = 32 W/m 2 (dt=6k) Air movement in space (convection): Asymmetric plumes of heat sources 0-15 % Air diffusion 0 +20 % Federation of European Heating, Ventilation and Air-conditioning Associations

Thermally Active Building Systems (TABS) Federation of European Heating, Ventilation and Air-conditioning Associations 16

Federation of European Heating, Ventilation and Air-conditioning Associations www.naturalcooling.com

Floor Cooling Federation of European Heating, Ventilation and Air-conditioning Associations 19

Displacement Ventilation Federation of European Heating, Ventilation and Air-conditioning Associations 21

Displacement Ventilation System Thermal displacement ventilation is based on cool air supply at low level and stratification of room air temperature and contaminants due to natural buoyancy forces of the heat gains. Federation of European Heating, Ventilation and Air-conditioning Associations 22

Height Lower Energy Consumption in Cooling and Better IAQ Contaminants are carried above the shift zone by convective plumes thus air in the occupied zone is cleaner By cooling occupied zone only, the required airflow rate & cooling capacity may be reduced Temperature, Contaminants Federation of European Heating, Ventilation and Air-conditioning Associations 23

Federation of European Heating, Ventilation and Air-conditioning Associations 24

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Air Distribution Principles in Auditoriums a) Supply air is contained between the rows. b) Supply air is foating down the stairways. 8 l/s,person 16 l/s,person Federation of European Heating, Ventilation and Air-conditioning Associations 27

Types and Variation of Current UFAD Supply Air Positive pressure plenum (unducted, push type) Grille, diffuser VAV-unit Neutral pressure plenum Ducted to VAV or Fan coil unit Unducted, pull type Fan powered VAV Fan coil unit Fan powered diffuser Return Air Ceiling plenum Ducted Partially ducted Unducted High sidewall grille (Floor plenum ducted to grille or fan coil unit) Federation of European Heating, Ventilation and Air-conditioning Associations 30

Height above floor level, z [m] Ceiling cooling elements combined with displacement ventilation Low velocity air supply combined with cooling elements at the ceiling level behave like mixing system when the cooling elements provide a substantial part of the cooling. 2,50 Cooled ceiling 2,00 1,50 1,00 0,50 0,00 0,8 1,0 1,2 1,4 Relative air temperature (relative to temp. at 0,1 m above the floor) = 0 = 0,4 = 0,5 = 0,6 = ratio of the cooled ceiling cooling output to the total cooling output (Tan 1998) Federation of European Heating, Ventilation and Air-conditioning Associations 31

Dedicated Outdoor Air System (DOAS) 100% outdoor air is delivered to each zone via its own ductwork Outdoor air is conditioned in DOAS unit Filtered / cooled / heated / dehumidified / humidified Exhaust fan & filter is integrated into a same air handling unit Air flow rate: To fulfill air flow rate specified by ASHRAE Std. 62.1 / EN 15251 or greater To satisfy cooling/dehumidification demand in space (sensible and latent) Can be either constant volume (CAV) or demand based Energy recovery can be integrated Predictable ventilation control and improved indoor air quality Energy efficiency is dependent on air volume and system design Good efficiency with water cooling (e.g. chilled beams and chilled ceilings) Federation of European Heating, Ventilation and Air-conditioning Associations 32

Cross-flow heat exchangers Separation of the two air flows No transfer of moisture or odour Easy maintenance Optional bypass & circulation air damper Federation of European Heating, Ventilation and Air-conditioning Associations

Thermal wheel heat exchanger Heat recovery up to 85% Transfer of latent heat possible Aluminium foil accumulator mass Speed 1-10 rpm Easy maintenance Federation of European Heating, Ventilation and Air-conditioning Associations

Latent (internal, external) and part of the sensible loads are taken care in AHU ideview 30 52 5.2 kw Round-around and cooling coil (10 kw) 70 kw (10 kw) 52 30 1218 913 41 O C 35 % 19 g 4 29 O C 53 % 13.3 g 24 O C 13 O C 5 706% 95 % 7 8 13.3 g 9.5 g 1218 913 17 O C 70 % 9.5 g 30 52 2 1 3 52 30 10 3.0 kw Sorption wheel 1621 lanview 509 400 712 9 26 O C 55 % 11.5 g 1218 913 2 g/kg from internal moisture sources, dependent on supply air volume 52 30 260 Federation of European Heating, Ventilation and Air-conditioning Associations 52 30

AHU selection without and with different energy recovery systems in Delhi during summer Indirect adiabatic Sensible wheel Direct adiabatic Delhi, summer Sorption wheel Crossflow heat exchanger No energy recovery Room air Supply air Federation of European Heating, Ventilation and Air-conditioning Associations

Temperature reduction with different energy recovery systems in Delhi during summer Delhi, summer Direct adiabatic Crossflow heat exchanger Sensible wheel Sorption wheel Indirect adiabatic Federation of European Heating, Ventilation and Air-conditioning Associations

Energy saving with different energy recovery systems in Delhi during summer Delhi, summer Direct adiabatic Crossflow heat exchanger Indirect adiabatic Sensible wheel Sorption wheel Federation of European Heating, Ventilation and Air-conditioning Associations

Moisture removal with different energy recovery systems in Delhi during summer Delhi, summer Direct adiabatic Sensible wheel Indirect adiabatic Crossflow heat exchanger Dew point 17 OC Internal moisture from people Sorption wheel Federation of European Heating, Ventilation and Air-conditioning Associations

Policies & Technologies for a Better Energy Future in India: Indo-European Cooperation REHVA and ISHRAE are organizing a seminar 7 th of March 2013, in Mumbai at 14.30 16.30 Chairs: Maija Virta, REHVA and Sushil K. Choudhury, ISHRAE 14:30 Energy efficient buildings: Energy Conservation Building Code and Building Star rating in India Bureau of Energy Efficiency, India 15.00 Energy efficient products: Ecodesign criteria in Europe and how it affects the industry in Europe and India by Alexandra Sombsthay, European Commission 15.30 Long term investor view: Why sustainable buildings are needed in India by Frank Hovorka, Head of real estate sustainability policy, Caisse des Dépôts, France 16.00 Business view: Better business in sustainable buildings by Rohan Parikh, 16.30 End of seminar Head Green Initiatives, Infosys, India Federation of European Heating, Ventilation and Air-conditioning Associations 40

Thank you for your attention maija@santrupti.com Federation of European Heating, Ventilation and Air-conditioning Associations