1 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Hugh CrowtherVice President, EngineeringHugh.Crowther@swegon.com

October 24, 2017

2 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

AGENDA

Ventilation Unit Primer

Centralized vs. Decentralized Ventilation Design

Winter Humidity Issues

Energy Impact - Sensible vs. Enthalpy Energy Recovery

Summary

Questions

1

2

3

4

5

6

3 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT PRIMER

PART 1

Integrating Swegon GOLD DOAS units with Mitsubishi VRF

4 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ENERGY RECOVERY VENTILATION UNITS

Total (Enthalpy) Energy Recovery

> Recover heat and humidity

> Raise temperature and humidity in winter, cool and dehumidify in summer

> Enthalpy plate enthalpy wheel

> Sometimes called Energy Recovery Ventilators (ERVs)

Sensible Energy Recovery

> Recover heat but not humidity

> Raise temperature in winter but not increase humidity ratio

> Plate, wheel, heat pipe, run around loops

> Sometimes called Heat Recovery Ventilators (HRVs)

5 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

CENTRALIZED VENTILATION UNIT EXAMPLES

6 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

DECENTRALIZED VENTILATION UNIT – WALL MOUNTED

7 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

DECENTRALIZED VENTILATION UNITS – CLOSET/CEILING MOUNTED

8 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – PLATE TYPE

9 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

VENTILATION UNIT – WHEEL TYPE

10 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

11 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

12 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

13 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

14 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

15 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

16 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

17 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

18 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VENTILATION UNIT – WHEEL TYPE

Extract

Outside

Supply

Exhaust

Extract Outside SupplyExhaust

19 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

DEFINITION OF EFFICIENCY (EFFECTIVENESS ETC.)

𝜺 =𝒄𝒇𝒎𝒔𝒂(𝑿𝒐𝒂 − 𝑿𝒔𝒂)

𝒄𝒇𝒎𝒎𝒊𝒏(𝑿𝒐𝒂 − 𝑿𝒓𝒂)𝜺 =

𝑿𝒓𝒂 − 𝑿𝒆𝒂 + 𝑷𝒆𝒍/𝒎 · 𝒄𝒑

(𝑿𝒓𝒂 − 𝑿𝒐𝒂)𝜺 =

(𝑿𝒐𝒂 − 𝑿𝒔𝒂)

(𝑿𝒐𝒂 − 𝑿𝒓𝒂)

20 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SENSIBLE ENERGY VENTILATION UNIT (HRV)WINTER OPERATION

Outside Air (OA)

Exhaust Air (EA)

Supply Air (SA)

Return Air (RA)

15°F 65°F

72°F23°F

Exhaust Air Fan Heat Exchanger Return Air Filter

Outside Air Filter Supply Air Fan

Outdoors Indoors

21 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

TOTAL ENERGY VENTILATION UNIT (ERV)WINTER OPERATION

Outside Air (OA)

Exhaust Air (EA)

Supply Air (SA)

Return Air (RA)

15°F, 82% RH 65°F, 36% RH

72°F, 31% RH23°F, 81% RH

Exhaust Air Fan Heat & Moisture Exchanger

Return Air Filter

Outside Air Filter Supply Air Fan

Outdoors Indoors

PHI Certification values:

> 84% heat recovery efficiency (min 75% required)

> 0.32 W/CFM (max 0.765 required)

Certified values, no PHI requirements:

> 84% moisture recovery efficiency

22 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

TOTAL ENERGY VENTILATION UNIT (ERV)SUMMER OPERATION

Outside Air (OA)

Exhaust Air (EA)

Supply Air (SA)

Return Air (RA)

88°F, 48% RH 77°F, 50% RH

75°F, 43% RH86°F, 43% RH

Exhaust Air Fan Heat & Moisture Exchanger

Return Air Filter

Outside Air Filter Supply Air Fan

Outdoors Indoors

PHI Certification values:

> None (min 75% required)

> 0.32 W/CFM (max 0.765 required)

Certified values, no PHI requirements:

> 84% heat recovery (rejection) efficiency

> 66% moisture recovery

23 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

CENTRALIZED VS. DECENTRALIZED VENTILATION DESIGN

PART 2

Integrating Swegon GOLD DOAS units with Mitsubishi VRF

24 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

CENTRALIZED VENTILATION DESIGN, (3) FLOORS, (1) ERV, (2) SHAFTS, (6) LONG DUCT RUNS

PENETRATIONS ERV1

Outside Air 1

Exhaust Air 1

Total 2

Occupied Space

Occupied Space

Occupied Space

Return Air

Exhaust Air

Supply AirOutside Air

25 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

DECENTRALIZED VENTILATION DESIGN(3) FLOORS, (1) ERV/ZONE, (0) SHAFTS, SHORT DUCTS

PENETRATIONS ERV1-6

Outside Air 6

Exhaust Air 6

Total 12

Occupied Space Occupied Space

Occupied Space Occupied Space

Occupied Space Occupied Space

ERV 1 ERV 2

ERV 3 ERV 4

ERV 5 ERV 6

26 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ENERGY RECOVERY VENTILATION UNITS

Decentralized

> Operating cost and maintenance is in tenants control

> No common area duct runs

> Minimal fire damper issues

> No Common mechanical room requirement – space savings

> Cost advantage - depends

Centralized

> Maintenance in control of building owner

> Far fewer envelope penetrations (pressure testing)

> Generally more efficient (Fans, energy recovery device) DOAS units

> Equipment noise away from tenants – easier to attenuate

> Doesn’t use up apartment space

> Cost advantage - depends

27 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

WINTER HUMIDITY ISSUES

PART 3

Integrating Swegon GOLD DOAS units with Mitsubishi VRF

28 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

WINTER HUMIDITY ISSUE

High humidity within apartment in cold weather creates uncomfortable indoor climate can cause condensation to form damage building, mold

29 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

CONDENSATION FORMATION

> The colder it gets, the easier humidity will form

> The higher the humidity level, the easier humidity will form

> Both at the same time is a bad thing

> Better glass helps (inside temperature is higher and stays above dew point longer)

30 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 1 –HIGH DENSITY APARTMENT

> ASHRAE Std 90.1 and Passive House construction

> Sensible (HRV) and Enthalpy (ERV) energy recovery

> Decentralized and centralized ventilation

31 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

HIGH DENSITY APARTMENT

32 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

HIGH DENSITY APARTMENT

> 952 ft²

> 3 bedroom, 2 bathroom

> Design Occupancy = 4

> Laundry in common area

> Ventilation rate = 85 cfm

> Std 90.1 Infiltration = 72 cfm

> PH Infiltration = 20 cfm

33 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 2 –LOW DENSITY APARTMENT

> ASHRAE Std 90.1 and Passive House construction

> Sensible (HRV) and Enthalpy (ERV) energy recovery

> Decentralized and centralized ventilation

34 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

LOW DENSITY APARTMENT

35 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

LOW DENSITY APARTMENT

> 853 ft²

> 2 bedroom, 2 bathroom

> Design Occupancy = 4

> Laundry in apartment

> Ventilation rate = 85 cfm

> Std 90.1 Infiltration = 141 cfm

> PH Infiltration = 39 cfm

36 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ESTIMATING HUMIDITY LOADS

37 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ESTIMATING HUMIDITY LOADS*

Source Pints Grains

5 Minute Shower 0.5 3650

Indoor drying of cloths 4-6 per load 29225-43840 per load

5-7 house plants 1/day 7300/day

Washing Dishes (Dinner, family of 4) 0.7 5100

Cooking (Dinner, Family of 4) 1.2 (1.5 with gas cooktop)

8770 (10950 with gas cooktop)

Respiration/Perspiration 0.4/hr 3040/hr

Evaporation, New Construction Materials 10+/day 73000+/day

1 Cord Green Firewood, stoed indoors for 6 mo 400-800 2.9M-5.8M

*Minnesota Extension Service, University of Minnesota

38 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

High Density 59.1 gr/lb

Low Density 52.7 gr/lb

HUMIDITY SOURCE ASSUMPTIONS

High Density 8770 gr/h

Low Density 8770 gr/h

High Density 5100 gr/h

Low Density 5100 gr/h

High Density 7300 gr/h

Low Density 3650 gr/h

High Density 12160 gr/h

Low Density 9120 gr/h

39 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

> Air Infiltration

> 0.18 cfm/ft2@ 0.2” wc (Std 90.1)

> 0.05 cfm/ft2@ 0.2’wc (PH)

> Permeation – ignored

> Ventilation air

> 85 cfm

> Sensible Energy Recovery (dry air)

> Total Energy Recovery (retain 80% of moisture)

DEHUMIDIFICATION

40 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 1 – HIGH DENSITY, DECENTRALIZED VENTILATION> HIGH DENSITY APARTMENT HAS high

internal humidity gain

> Infiltration from Std 90.1 construction helps dry out space

> Tight PH building builds up humidity in space

> Sensible recovery device recovers heat but air is dry – helps dry out space

> Total energy recovery device recoups 80% of humidity – causes humidity to increase

Dehumidification Result

Humidity

Gain

Infiltration Sensible

Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

33330 6240 7367 58 50.5

Passive House

Construction

33330 1733 7367 66 56.5

Sensible (HRV) Energy Recovery

Dehumidification Result

Humidity

Gain

Infiltration Total Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

33330 6240 1473 69 59

Passive House

Construction

33330 1733 1473 77 65.7

Total (ERV) Energy Recovery

41 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 1 – HIGH DENSITY, CENTRALIZED VENTILATION> High Density apartment has high internal

humidity gain

> Infiltration from Std 90.1 construction helps dry out space

> Tight PH building builds up humidity in space

> Centralized sensible energy device behaves the same as decentralized

> Diversity from being connected to multiple apartments reduces increase in RH

Sensible (HRV) Energy Recovery

Total (ERV) Energy Recovery

Dehumidification Result

Humidity

Gain

Infiltration Sensible

Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

33330 6240 7367 58 50.5

Passive House

Construction

33330 1733 7367 66 56.5

Dehumidification Result

Humidity

Gain

Infiltration Total Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

33330 6240 2947 66 56.5

Passive House

Construction

33330 1733 2947 74 63.6

42 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 2 – LOW DENSITY, DECENTRALIZED VENTILATION> Low density apartment has 80%

humidity gain for same volume

> Infiltration from Std 90.1 construction helps dry out space

> Tight PH building builds up humidity in space

> Sensible recovery device recovers heat but air is dry – helps dry out space

> Total energy recovery device recoups 80% of humidity – but not to an unacceptable level

Sensible (HRV) Energy Recovery

Total (ERV) Energy Recovery

Dehumidification Result

Humidity

Gain

Infiltration Sensible

Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

26640 12230 7367 37 31.9

Passive House

Construction

26640 3397 7367 55 47.2

Dehumidification Result

Humidity

Gain

Infiltration Total Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

26640 12230.4 7367 69 42

Passive House

Construction

26640 3397 7367 66 56.5

43 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 2 – LOW DENSITY, CENTRALIZED VENTILATION> Low density apartment has 80%

humidity gain for same volume

> Infiltration from Std 90.1 construction helps dry out space

> Tight PH building builds up humidity in space

> Centralized sensible energy device behaves the same as decentralized

> Diversity from being connected to multiple apartments and lower humidity gain make total energy preferable

Sensible (HRV) Energy Recovery

Total (ERV) Energy Recovery

Dehumidification Result

Humidity

Gain

Infiltration Sensible

Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

26640 12230 7367 37 31.9

Passive House

Construction

26640 3397 7367 55 47.2

Dehumidification Result

Humidity

Gain

Infiltration Total Energy

Recovery

Ventilation

New Hum

Ratio 72F

New Rel.

Hum. at

72F

gr/hr gr/hr gr/hr gr/lb %

Std 90.1

Construction

26640 12230.4 7367 66 39.5

Passive House

Construction

26640 3397 7367 63 53.9

44 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Scenario Density Ventilation Std. Sensible vs. Total New Rel. Hum. At 72F (%)

1 HIGH DECENTRALIZED

90.1 Sensible 50.5

Total 59

PH Sensible 56.5

Total 65.7

1 HIGH CENTRALIZED

90.1 Sensible 50.5

Total 56.5

PH Sensible 56.5

Total 63.6

2 LOW DECENTRALIZED

90.1 Sensible 31.9

Total 42

PH Sensible 47.2

Total 56.5

2 LOW CENTRALIZED

90.1 Sensible 31.9

Total 39.5

PH Sensible 47.2

Total 53.9

SUMMARY

45 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

WINTER HUMIDITY SUMMARY

Passive House construction is tight

Ultra low leakage rates can cause humidity to build up in apartments especially high density apartments

Decentralized Total Energy Recovery Ventilation has risk

Humidity recovery causes humidity to build up to unacceptable levels. It may not be an issue in low density apartments

Centralized Ventilation units can help

The diversity from connecting to multiple apartments can reduce humidity build up and allow additional savings from total energy recovery

46 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ENERGY IMPACT –SENSIBLE VS. ENTHALPY ENERGY RECOVERY

PART 4

Integrating Swegon GOLD DOAS units with Mitsubishi VRF

47 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

ENERGY MODELLING> DOAS unit energy modelling program

> Compare two systems side by side

> Enthalpy Wheel vs. sensible wheel

> Scenario 1 – No cooling, hot water heating

> Scenario 2 - VRF DX cooling w/ HGRH and heat pump heating

48 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

MODEL SETUP

49 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

MODEL SETUP

50 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

WHEEL FROST CONTROL

Total recovery much greater than sensible due to lower frost point

Almost twice winter energy recovery

Wheel speed vs. energy transfer not linear

Must slow wheel down to a few rpm to get capacity reduction

51 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 1- NO COOLING

52 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Scenario 2 - VRF Heating and Cooling

53 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VRF – Ventilation Unit Integrated Controls

54 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VRF Electronic Expansion Devices

55 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

VRF – Hot Gas Reheat Solution

56 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SCENARIO 2 - VRF COOLING AND HEATING

57 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SUMMARY

PART 5

58 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

SUMMARY

Centralized vs. decentralized ventilation depends on the application

The are many parameters including technical and cost that impact this decision. Being able to seal the building for a pressure test should not be overlooked especially on tall buildings

Passive House construction and high humidity in winter should be considered

Be careful with high density apartments and decentralized total energy recovery. Centralized total energy recovery should be okay, Low density apartments should be okay but check!

Total Energy recovery saves energy and reduces operating cost

Total energy recovers 5-15% more sensible energy in winter plus maintain indoor humidity. It dehumidifies in summer. It reduces size of air conditioning by 25%

59 Ventilation Design Considerations for Passive House Multifamily Residential Buildings

Questions?