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Ventilation Design Considerations for Passive House ...€¦ · 43 Ventilation Design...
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1 Ventilation Design Considerations for Passive House Multifamily Residential Buildings
Ventilation Design Considerations for Passive House Multifamily Residential Buildings
Hugh CrowtherVice President, [email protected]
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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?