Modern HVAC-systems for nearly zero energy buildings

Federation of European Heating, Ventilation and Air-conditioning Associations 1

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

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

• 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

Focus of this presentation is on

underlined HVAC technologies

2


Passive Chilled Beams

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.


Active Chilled Beams

5


Chilled Beam Operation

1 2 3

4

5

6

1. Primary air

(dehumidificated

outdoor air) supply into

supply air chamber

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

5. Cold water connection

6. Warm water connection


Chilled Beam Operation

Exposed chilled beam for installations

without suspended ceiling

Closed chilled beam for installations

with suspended ceiling

Vanhat tiedostot/Benkulle/Videos/Beam_funtionality.wmv






Chilled Ceilings

12



Total Cooling Capacity

26 OC

19 OC

40 OC 37 OC

26 OC

Radiation: 5.5 W/m2,K

toperative = 25 OC, tsurface = 19 OC, Pradiation = 33 W/m2 (dt=6K)

26 OC

19 OC

26 OC 40 OC

37 OC

Natural Convection:

Pconvection = 65 – 33 = 32 W/m2 (dt=6K)

Air movement in space (convection):

Asymmetric plumes of heat sources 0…-15 %

Air diffusion 0…+20 %



Thermally Active Building Systems (TABS)


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


Floor Cooling



Displacement Ventilation

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.

22


Lower Energy Consumption in Cooling

and Better IAQ H

eig

ht

Temperature, Contaminants

By cooling occupied zone only,

the required airflow rate &

cooling capacity may be reduced

Contaminants are carried above

the shift zone by convective

plumes thus air in the occupied

zone is cleaner

23




?

26


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

27



29


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)

30


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.

0,00

0,50

1,00

1,50

2,00

2,50

Hei

gh

t ab

ove

flo

or

leve

l, z

[m

]

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)

Cooled ceiling

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)


• Separation of the two air flows

• No transfer of moisture or odour

• Easy maintenance

• Optional bypass & circulation air damper

Cross-flow heat exchangers


• Heat recovery up to 85%

• Transfer of latent heat possible

• Aluminium foil accumulator mass

• Speed 1 - 10 rpm

• Easy maintenance

Thermal wheel heat exchanger


Latent (internal, external) and part of the

sensible loads are taken care in AHU

Wolf GmbH84048 Mainburg

Telefon 08751/74-0Fax 08751/741574www.wolf-klimatechnik.de

Project no.:

KG Top 130

NameResponsible:

Date

15.11.2012

Project name: Sorption wheel with diffusion sections

Client:

Position:

/

Side view

12 3

9

5 6 7 84

1010171017

2034

529131218

30

529131218

3052

913121830

52

913121830

Planview

10

R1

912 3

712 509 400 712 712

3045

509 400 712

1621

1932305

1322

52

1218 91330 260 52

1218 91330

120

Planview

5 6 7 8

R1

4 12 3

712 509 400 712 712 610 610 305

4570

3051322 1932

521218 913

30

120

52

1218 91330 260

R1 = Access door

Total weight ca. 845kg 1 Rotary heat exchanger ca. 300kg

2 Air diffusion section ca. 16kg

3 Air diffusion section ca. 22kg

4 Bag filter F9 (short bags) ca. 48kg

5 Fan section ca. 87kg

6 Cooling section ca. 58kg

7 Cooling section ca. 120kg

8 Heating section ca. 43kg

9 Bagfilter F7 (short) ca. 31kg

10 Fan section ca. 120kg

Airvolume-supply side: 10000 m³/h

Airvolume extract: 9500 m³/h

Length of projection of damper linkage max. 120 mm fromexternal unit surface, parallel to damper fins.

41 OC

35 %

19 g

26 OC

55 %

11.5 g

24 OC

70 %

13.3 g

13 OC

95 %

9.5 g

(10 kW) 70 kW

Sorption wheel 3.0 kW

5.2 kW

17 OC

70 %

9.5 g

(10 kW)

29 OC

53 %

13.3 g

Round-around and cooling coil

2 g/kg from internal

moisture sources,

dependent on supply air

volume


No energy recovery

Delhi, summer

AHU selection without and with different energy

recovery systems in Delhi during summer

Room air

Direct

adiabatic

Indirect adiabatic

Sorption wheel

Crossflow heat exchanger

Sensible wheel

Supply air


Delhi, summer

Temperature reduction with different energy


Direct adiabatic

Sorption wheel

Sensible wheel

Indirect adiabatic



Delhi, summer

Energy saving with different energy


Direct adiabatic

Indirect adiabatic

Sorption wheel


Sensible wheel


Delhi, summer

Moisture removal with different energy


Dew point

17 OC

Direct adiabatic

Sorption wheel

Sensible wheel

Indirect adiabatic

Crossflow heat

exchanger

Internal moisture from people


Policies & Technologies for a Better Energy Future

in India: Indo-European Cooperation

REHVA and ISHRAE are organizing a seminar

7th 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, Head Green Initiatives, Infosys, India

16.30 End of seminar

40


Thank you

for your

attention

[email protected]

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Modern HVAC-systems for nearly zero energy buildings