dcv case study on comfort and energy - swegon air academy · dcv case study on comfort and energy...

DCV case study

on comfort and energy

Ing. Petra Vladykova Bednarova, Ph.D. (Swegon AB) with Francesco Errico (Padua University)

in cooperation with supervisors

Ing. Michele De Carli, Prof. (Padua University)

Arch. Markus Kalo, M.Sc. (Swegon AB)

Dennis Johansson, Ph.D. (Lund University)

Swegon Air Academy, Mikkeli, Finland, March 17th, 2016

Contents

1. Survey of project “Engelsons” and monitoring

2. Indoor environmental evaluation

3. Power and energy calculation

4. IDA ICE modelling

5. Energy and economic evaluation

6. Conclusions

7. A bit more…2

Objectives

• Verify the IEQ (indoor environmental quality) parameters for a solution system

• Compare existing CAV (constant air volume) system with CAV model to verify the model

• Modelling of VAV (variable air volume) and DCV (demand controlled ventilation) systems to evaluate effects and benefits

• What is CAV, VAV and DCV?

3

Survey and monitoring Indoor environmental evaluation Power and energy calculation IDA ICE modelling Energy evaluation Economic evaluation

Engelsons in Falkenberg

Location Engelsons Postorder AB

4

2 200 m2 Retail & Office building


HVAC system

5

TA/FA1: 1 000 l/s

TA/FA2: 1 800 l/s

TA/FA3: 1 200 l/s

Exhaust

Supply

Recirculation

Extract

Heating and Cooling Air Air Energy

Heating

fan coils

Production Diffusion

Electric Source

Outdoor


HVAC sub-systems

TA/FA1: 1 000 l/s(3 600 m3/h)

warehouse

TA/FA3: 1 200 l/s(4 300 m3/h)

rented office

TA/FA2: 1 800 l/s → 2 100 l/s 6 500 m3/h → 7 600 m3/h

office, retail and packing6


Zones

7

OFFICE

Air water

725 l/s(2 600 m3/h)

481 m2

RETAIL

Air

+ air water (extra)

900 l/s(3 200 m3/h)

439 m2

PACKING

Air + air water

+ air water (extra)

175 l/s → 475 l/s (650 m3/h → 1 700 m3/h)

514 m2

+ heating fan coils


Monitoring systems

Air handling unit data (AHUD)Apr 2011 – Nov 2013

Integrated monitoring system

Temperature, relative humidity

Pressure

Airflows

Calculated SFP (specific fan

power), recovery efficiency

8

Indoor environment (IED)Oct 2011 – Feb 2013

Hobo loggers, remote access

Temperature, relative humidity


AHU data

Airflow Night (Unoccupied) mode

9

• CAV

• Airflow increase

• No reduction in SFP

1

1,4

1,8

2,2

2,6

SF

P [kW

/(m

3/s

)]

Specific fan power (SFP)

SFPDAYh(6-18)

SFPNIGHTh(19-5)

200

600

1 000

1 400

1 800

2 200

2 600

Airflow

[l/s]

Airflow ( zoom 200 - 2 600 l/s )(720 m3/h - 9 360 m3/h)

Extractairflow

Supplyairflow


Indoor environmental data

10

0

10

20

30

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan

[°C

]

Airflow 1 800 l/s (6 500 m3/h)

2011

0

10

20

30


[°C

]

Jan-Apr airflow 1 800 l/s ; Apr-Dec airflow 2 100 l/s (7 500 m3/h)

2012

0

10

20

30

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

[°C

]

Airflow 2 100 l/s

2013


Reference year on records

• 100 % of IED

• CAV 1 800 l/s

( 3 600 m3/h)

• Weather data

from SMHI

11

0

10

20

30


[°C

]

RYR


Indoor evironmental evaluation

• Main purpose of a HVAC system is to ensure the right

comfort

• Complaints: are they justified / validated?

• Long period comfort

• Energy category of the building

12


Weekly outdoor minimum temperature

16

• UNI EN 15251

• Complaints rejected

-20

-15

-10

-5

0

15

17

19

21

23

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

]

Packing zone: air temperature

Packing height 1,1m Outdoor temperature

-20

-15

-10

-5

0

15

17

19

21

23

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

]

Retail zone: air temperature

Retail height 1,1m Outdoor temperature

-20

-15

-10

-5

0

15

17

19

21

23

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

] Office zone: air temperature

Office 2110 height 1,1m Outdoor temperature

Minimum recommended temperature EN 15251


Weekly outdoor maximum temperature

17

• Nothing to highlight for

warm discomfort

0

7

14

21

28

20

22

24

26

28

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

] Office zone: air temperature

Office 2110 height 1,1m Outdoor temperature

0

7

14

21

28

20

22

24

26

28

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

] Packing zone: air temperature

Packing height 1,1m Outdoor temperature

0

7

14

21

28

20

22

24

26

28

Sun Tue Thu Sat

Te

mp

era

ture

[⁰C

] Retail zone: air temperature

Retail height 1,1m Outdoor temperature

Maximum recommended temperature EN 15251


Long period comfort

18

• WT: Weighted time

• PPD & PMV based on

adapting clothing

and activity

• Over-cooling in office is

due to manual settings

0100200300400500


Office zone: WTwarm/cool

WT Warm WT cool

Annual Wcool= 2 007

Annual Wwarm= 0

0100200300400500

Jan Feb Mar Apr May Jun Jul AugSep Oct NovDec

Retail zone: WTwarm/cool

WT warm WT cool

Annual Wcool= 0

Annual Wwarm= 780

0100200300400500

Jan Feb Mar Apr May Jun Jul AugSep Oct NovDec

Packing zone: WTwarm/cool

WT warm WT cool

Annual Wcool= 0

Annual Wwarm= 1 017


Building energy category

Winter category

Category 1

Office

Category 2

Retail, Packing

Category 3

No zones

Detailed data distribution

0%

20%

40%

60%

80%

100%

<19 15-16 16-18 17,5-21 20,5-22 22-23 >25

Temperature intervals [°C]

Retail zone: winter detailed data concentration

19

0%

20%

40%

60%

80%

100%

<19 15-16 16-18 17,5-21 20,5-22 22-23 >25


Packing zone: winter detailed data concentration


Building energy category

Summer category Detailed data distribution

20

Potential to improve the

energy category

Category 1

Retail, packing

Category 2

No zones

Category 3

No zones

Uncategorised

Office

0%

20%

40%

60%

80%

100%

<22 22-23 23-23,5 23,5-25,5 25,5-26 26-27 >27


Office zone: summer detailed data concentration


Indoor environmental focus

• Complaints not justified

• Overheating or overcooling

• Investigation on thermal comfort

• Wrong regulation in night mode

Importance of continuous monitoring

21


Energy calculation

22

Sub-systemAnnual specific energy

[kWhe/m2·a]

Monitored zones(calculated)

91

Rented Office(estimated)

~41

Warehouse(estimated)

~100

Overall ~ 230

0

1

2

3

4


[kW

he/m

2]

Retail zone: specific electric energy

Electric for fans Electric for thermal

Annual

43 kWhe/(m2·a)

0

1

2

3

4


[kW

he/m

2]

Packing zone: specific electric energy


Annual

7 kWhe/(m2·a)

0

1

2

3

4


[kW

he/m

2]

Office zone: specific electric energy


Annual

41 kWhe/(m2·a)


IDA ICE model

23

U-value

[W/(m·K)]Surface [m2]

Walls 0,315 1 483

Floor 0,146 2 203

Ceiling 0,193 2 203

Openings 1,2 106

• CAV-VAV-DCV-DCV class 1

• Dynamic simulation software


Setpoints for the model

RYR weather – SMHI station Torup A

Zone set-points

Minimum temperature

[ºC]

Maximum temperature

[ºC]

CAV airflow

[l/(s·m2)]Occupied Unoccupied Occupied Unoccupied

Office 1,58 21,5 21,5 21,5 21,5

Retail 2,03 21 20 21,9 23,9

Packing 0,35 20,6 20,1 22,1 24,1

24


Model validation

25

ZoneAnnual specific energy

[kWhe/(m2∙a)]

Annual

average drift

Calculated Model

Office 42,97 41,84 - 0,6%

Retail 40,05 41,02 + 1,1%

Packing 7 4,32 - 37,3%

0

2

4

6


[kW

he/m

2]

Office zone: comparison between model and

calculation

CAV MODEL CALCULATED

Annual average

drift - 0,6%


Model adjustment

• Change of use/activity for

packing zone

• Adjustments

– Fan coils

– Increase of airflow

• IWEC2 weather data

26

0

5

10

15

20

25

Jan Mar Jun Sep Dec

Te

mp

era

ture

[ºC

]

Packing zone: simulated air temperature


Model adjustment

27

4,32

22,21

0

15

30

CAV_RYR CAV

[kW

he/(

m2.a

)]

Packing zone: specific simulated energy after model

adjustment

+414%

ZoneAnnual specific energy

[kWhe/(m2·a)]

Percentage of

change

CAV_RYR CAV

Office 41,84 35,51 -15%

Retail 41,02 33,08 -19%

Packing 4,32 22,21 +414%

Overall building ~230


CAV – VAV – DCV – DCVclass1

Zone set-points

Minimum temperature [ºC] Maximum temperature [ºC]

CAV airflow [l/(s·m2)] Occupied Unoccupied Occupied Unoccupied

Office 1,58 21,5 21,5 21,5 21,5

Retail 2,03 21 20 21,9 23,9

Packing 0,95 20,6 20,1 22,1 24,128



29

Unoccupied period

• Fresh air

0,35 l/(s·m2)

• Δt ±2ºC



30

Minimum

airflow

0,35 l/(s∙m2)



31

Temperature set-points for DCVclass1

ZoneMinimum

temperature [⁰C]

Maximum

temperature [⁰C]

Office 22 24,5

Retail 19 23

Packing 19 23


Energy results

32

System improvement scenario – Energy saving

Cooling [kWhe/a] Ventilation [kWhe/a] Heating [kWhe/a] Overall [kWhe/a]

CAV – DCV -3 100 6 200 5 800 23 100 -54%

VAV – DCV 3 800 7 700 2 900 14 300 -42%

CAV – DCVclass1 1 400 13 900 10 300 24 400 -59%

VAV – DCVclass1 4 500 7 600 4 500 16 600 -49%

10 000

20 000

30 000

40 000

50 000

CAV VAV DCV DCVclass1

[kW

he/a

]

Cooling

Heating

Ventilation

Existing

100%

75%

50%

25%


Economic evaluationInvestment cost

• AHU downsize

• Downsize central

ducts and risers

• Extra equipment and

installation

System

improvement

Additional

investment

CAV – DCV + 12%

VAV – DCV + 8%

33


Economic evaluation

34

Distributed energy

Operating costs

Purchased energy

20 000

40 000

60 000

80 000

100 000

[kWhe; kWht; kWht]Final energy demanded

[kWhe; kWhe; kWhe]Purchased energy

Installed HP+ heat recovery

[kWhe; kWhe; kWhe]Purchased energy Scenario (DH-CH)

+ heat recovery

kW

h Ventilation

Heating

Cooling

With heat pump system

(existing)

With district heating & chiller system

(traditional)


Economic results

35

System improvement scenario – Economic saving

Production scenario (HP) Production scenario (DH – CH)

[€/a] [%] [€/a] [%]

CAV – DCV 3 100 54% 8 400 51%

VAV – DCV 1 900 42% 2 800 26%

CAV – DCVclass1 3 500 54% 9 100 51%

VAV – DCVclass1 2 300 49% 3 500 32%

€

€ 3 000

€ 6 000

€ 9 000

€ 12 000

€ 15 000

€ 18 000

CAV VAV DCV DCVclass1

Op

era

tin

g c

osts

[€

]

(DH-CH)Cooling

(DH-CH)Heating

(DH-CH)Ventilation

(HP)Cooling

(HP) Heating

(HP)Ventilation

DH-CH

HP


Economic results

Installed (HP) scenarioTheoretical (DH – CH)

scenario

36

1,911,73

2,061,77

0

1

2

3

Ye

ars

Installed HP: payback time

0,72 0,66

1,451,15

0

1

2

3

Ye

ars

Scenario (DH-CH): payback time


Energy & economic comparison focus

• CAV, VAV, DCV, DCVclass1

• CAV – DCV / DCVclass1

VAV – DCV / DCVclass1

• System production: HP, (DH – CH)

• Payback period

Assumed

occupation profiles and occupancy rate

37

Conclusion I.Indoor environmental evaluation

• Right indoor climate as a base line

– Wellness for people

– No complaints, following legislation

– Efficiency in work, less sick leave, etc.

• Continuous monitoring

– To be sure that a monitoring system should be in place for

optimisation and possible deviations

– Improvement of monitoring38

http://dqbasmyouzti2.cloudfront.net/content/images/articles/KickingBack.jpg

Conclusion II.Importance of detailed information

• When activities change in a building, the climate

demands and distribution should be re-evaluated

• Central and remote access to HVAC building system to

have a valid overview of the building

• Enable the work of the facility manager

39

http://rebeccagovehumphries.files.wordpress.com/2009/10/climb-stack-of-paper.jpg

Conclusion III.Models and simulations

Wide margin of improvement

• Demand controlled system

– Best case: CAV – DCV (50% energy reduction)

• Different production systems

– Best case payback: less effective production plant

40

http://hirportal.sikerado.hu/images/kep/201103/paks.jpg

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQJz_GMTrRv5F4gTT9YWVrllS0Kk7l1zlRGiNqCwjIgH98hbyD4Ag

Conclusion IV.Why a DCV system

• Additional investment +10% • annual saving 50%

• fast payback period (less than 2 years)

• Increased facility value

• Improved indoor comfort• increased productivity

• Commercials and marketing for the activity

Decrease of energy use

Decrease of annual operating costs

41

Conclusion V.Improvements in the installed system

• Airflow balance

• Appropriate indoor temperature set-points

• Check the night-mode protocol settings

The changes during the years were not followed by a

re-evaluation and re-balancing of the entire system.

42

http://www.conrad.it/medias/global/ce/8000_8999/8200/8240/8240/824097_BB_01_FB.EPS_1000.jpg

Conclusion VI.Improvements of the installed system

• Update control system

• Simple DCV system

43

http://www.conrad.it/medias/global/ce/8000_8999/8200/8240/8240/824097_BB_01_FB.EPS_1000.jpg

Energy saving +50%

Payback < 2 years

Conclusion

44

In commercial buildings it is economically viable to choose

a DCV system in order to increase the comfort and

decrease the energy use by up 50%.

A DCV system achieves the highest comfort with the lowest

possible operating energy.

A system fitted for people and for their needs.

http://www.cleanandgreenlaw.com/files/2013/01/Puzzle-piece.jpg

DCV case study on comfort and energy

A bit more…

• Energy monitoring is a large part of future challenge for

nZEB.

• European Project iSERVcmb (concluded in 2014) show

a result of continuous monitoring of 330 buildings the

project reached an average energy consumption

reduction of 9%-33%.

• This reduction achieved with measures with no cost or

low cost, achieving payback periods of investment of

less than one year. (www.iservcmb.info).

45

http://www.iservcmb.info/

Literature

• Errico, F.: “DCV case study on comfort and energy”

• Mysen, M.: “Good indoor air quality and low-energy

consumptions in buildings”

• CLIMA Conference 2010: “DCV workshop”

• Maripuu M.: “DCV for better IAQ and energy efficiency”

• iSERVcmb: www.iservcmb.info

• And more at www.swegonairacademy.com

46

http://www.iservcmb.info/

http://www.swegonairacademy.com/

Thank you.

Questions?

Petra Vladykova Bednarova

& Francesco Errico

[email protected]

[email protected]

47http://fotoclou.blogspot.it/2011/01/l-alba-vista-dallo-spazio.html

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