2021
Up and Running with the Passive House Planning Package (9.7 IP) Module 3 | Class 2 | Cooling
PHPP SETPOINTS
NYPH: Up and Running with PHPP
1
2021
bldgtyp | NYPH
This curve represents the ‘most’ moisture that air at some temperature can ‘hold’
Air at 68 F can ‘hold’ about 0.145 lb-moisture/lb-air at most
Cold Air bldgtyp | NYPH
NYPH: Up and Running with PHPP
Hot Air Psychrometric Chart: Andrew Marsh | https://drajmarsh.bitbucket.io/psychro-chart2d.html
2
2021
Mold risk ~55F Condensation risk ~49F
PHPP Winter Setpoint 68F [ Max 50% RH ]
bldgtyp | NYPH
Psychrometric Chart: Andrew Marsh | https://drajmarsh.bitbucket.io/psychro-chart2d.html
ISO7730:2005 PMV Air Velocity: 20 m/s Clothing: 1.0 Clo. Activity: 1.0 Met. Mean Radiant Temp: 68F
PHPP Winter Setpoint 68F [ Max 50% RH ]
bldgtyp | NYPH
NYPH: Up and Running with PHPP
Psychrometric Chart: Andrew Marsh | https://drajmarsh.bitbucket.io/psychro-chart2d.html
3
2021
ISO7730:2005 PMV Air Velocity: 20 m/s Clothing: 1.0 Clo. Activity: 1.0 Met. Mean Radiant Temp: 77F
PHPP Summer Setpoint 77F [ Max 60% RH ]
PHPP Winter Setpoint 68F [ Max 50% RH ]
bldgtyp | NYPH
Psychrometric Chart: Andrew Marsh | https://drajmarsh.bitbucket.io/psychro-chart2d.html
ASHRAE 55:2017 PMV Air Velocity: 20 m/s Clothing: 1.0 Clo. Activity: 1.0 Met. Mean Radiant Temp: 68F
PHPP Summer Setpoint 77F [ Max 60% RH ]
PHPP Winter Setpoint 68F [ Max 50% RH ]
bldgtyp | NYPH
NYPH: Up and Running with PHPP
Psychrometric Chart: Andrew Marsh | https://drajmarsh.bitbucket.io/psychro-chart2d.html
4
2021
PHPP Summer Setpoint 77F [ Max 60% RH ]
Summer Comfort Zone
bldgtyp | NYPH
One way or another, you must keep the building comfortable in Summer. In the PHPP, and for Passive House Certification, you can use either:
‘Passive’ Cooling
‘Active’ Cooling
bldgtyp | NYPH
NYPH: Up and Running with PHPP
5
2021
One way or another, you must keep the building comfortable in Summer. In the PHPP, and for Passive House Certification, you can use either:
‘Passive’ Cooling
‘Active’ Cooling
• Keep the building’s interior Temp <77F for 90% of the hours of the year • Keep the building’s interior Humidity <0.012 lb/lb for 80% of the hours of the year
• Keep the building’s interior Temp <77F for 90% of the hours of the year • Keep the building’s interior Humidity <0.012 lb/lb for 80% of the hours of the year • Meet the Annual Cooling Energy Demand limit for your location
bldgtyp | NYPH
PASSIVE COOLING
NYPH: Up and Running with PHPP
6
2021
Reduce Gains - Insulation - Shading, Shading, Shading - Airsealing (humidity) - Efficient Appliances Increase Losses - Ventilation - HRV ‘Bypass’
bldgtyp | NYPH
Three important material parameters can be applied to the opaque areas. These parameters are used to determine heat gains through these surfaces.
bldgtyp | NYPH
NYPH: Up and Running with PHPP
7
2021
Heating Demand (kBtu/ft2 )
Cooling Demand (kBtu/ft2 )
White Surface (e = 0.40)
4.61
5.27
Black Surface (e = 0.95)
4.36
5.66
Shading = 0.4
4.61
5.27
Shading = 0.7
4.56
5.47
Shading = 1.0
4.52
5.64
bldgtyp | NYPH
Thermal Mass The thermal storage capacity of a material is a product of its specific heat capacity (Cp) and its density (ρ)
bldgtyp | NYPH
NYPH: Up and Running with PHPP
Source: Grondzik. Mechanical and Electrical Equipment for Buildings
8
2021
bldgtyp | NYPH
The design flow rate for the ventilation system. Note that in summer, the total ACH (including the effect of windows) should be higher than in winter (~50% higher) and ERV selection should be made accordingly.
Ventilator ‘Summer Bypass’
HR/ERV CORE
bldgtyp | NYPH
NYPH: Up and Running with PHPP
9
2021
Any extract only ventilation (e.g., non-recirculating range hoods, exhausting clothes dryers, etc.) must be added here
bldgtyp | NYPH
bldgtyp | NYPH
NYPH: Up and Running with PHPP
10
2021
Operable Window Ventilation The PHPP uses the average ext. temps as well as the ‘Summer Temperature Amplitude’ value in order to calculate the total monthly losses from window ventilation.
bldgtyp | NYPH
Without Night Ventilation
With Night Ventilation
The primary benefit comes in reducing the shoulder season cooling energy demand. This is especially important in buildings with high solar gains (glass-y).
bldgtyp | NYPH
NYPH: Up and Running with PHPP
11
2021
ACTIVE COOLING
How do you calculate the energy needed to cool the building over the entire summer period?
bldgtyp | NYPH
NYPH: Up and Running with PHPP
12
2021
kBtu / year
A: QC = QS + QI – [hcool Transmission Losses
QT
Ventilation Losses
QV
(QT + QV)] Internal Gains
Solar Gains Cooling Demand Energy
QI
QS
QC Transmisson Gains
Heat Losses
Heat Gains
bldgtyp | NYPH
Monthly Sensible Cooling Energy Demand bldgtyp | NYPH
NYPH: Up and Running with PHPP
13
2021
bldgtyp | NYPH
qc = qc-sensible + qc-latent qc-latent = Water Vapor Reduction (dehumidification) Total amount of cooling energy required per year to ensure an acceptable internal relative humidity (0.012 lb/lb ≈ 60% RH at 77F) throughout the cooling period If average external dew point in your climate is 55.4 F or above for any 1 month period then an additional allowance is added to qc-sensible for dehumidification energy required bldgtyp | NYPH
NYPH: Up and Running with PHPP
14
2021
Certification Latent Cooling Allowance City, Country
Total Annual Cooling Demand (sensible + latent) – kBtu/ft2·yr
Madrid, Spain
4.75
Melbourne, Australia
4.75
New York (NY), USA
5.39
Beijing, China
6.02
Seoul, Korea
6.02
Austin (TX), USA
6.97
Shanghai, China
7.6
Miami (FL), USA
16.5
Manila, Philippines
22.5
Acapulco, Mexico
22.5
bldgtyp | NYPH
Where does the Moisture Come From? 1) External moisture leaking into the building: • Infiltration – air leaks in the building envelope • Window and Door operation 2) External moisture being brought into the building: • Mechanical Ventilation (HRV/ERV/Enthalpy wheel) • Natural ventilation (if applicable) 3) Internal moisture sources: • Cooking • Showering/bathing • House plants • Human activity • Clothes washing/drying • Dishwashing
bldgtyp | NYPH
NYPH: Up and Running with PHPP
15
2021
Q: What happens if the air coming into the home during summer (through windows or the H/ERV) is up here?
A: We have to remove moisture (dehumidify). That takes energy.
PHPP Summer Setpoint 77F [ Max 60% RH ]
bldgtyp | NYPH
Airtightness Can Help Peak Moisture Load (grains/hour)
14,0 00 12,0 00 10,0 00 8,00 0 Less Moisture Coming In
6,00 0 4,00 0 2,00 0
More Airtight -
0.
0
0.
5
1.
0
1.
5
2.
0
2.
5
3.
0
3.
5
4.
0
4.
5
5.
0
5.
5
6.
0
6.
5
7.
0
7.
5
8.
0
Building Airtightness [ ACH@50 ]
bldgtyp | NYPH
NYPH: Up and Running with PHPP
BLDGTYP: Mayers House. 2016
16
2021
ERVs Can Help Indoors (cooler & drier)
Outdoors (hotter & more humid)
In an ERV, when the relatively humid outdoor air passes by the relatively dry indoor air, the moisture moves from ‘wetter’ to ‘drier’ (higher vapor pressure to lower vapor pressure). The efficiency of this process will vary by ERV model.
Note: the reverse of this process is also true which is why in winter an ERV can help to maintain higher indoor RH levels even when the outdoor air is low RH.
bldgtyp | NYPH
Can’t Do Much About the People
Internal Humidity Sources [lb moisture/(1000 ft3/h)] = ( Moisture-Load × #Occupants) / TFA
bldgtyp | NYPH
NYPH: Up and Running with PHPP
17
2021
Using an ERV with high efficiency moisture recovery can affect this part
There is very little we can do to affect the moisture loads on the building. They are primarily a function of the climate. After building airtight and using an efficient ERV, the best thing we can do is choose very efficient active cooling equipment.
Peak Moisture Load (grains/hour)
10,0 00 9,00 0 8,00 0
Making the building more airtight can reduce this part
7,00 0 6,00 0
Basically nothing we can do about this part…
5,00 0 4,00 0 3,00 0 2,00 0 1,00 0 F rom Air Leakage
F rom Ve ntilation
F rom I ntern al So urces
bldgtyp | NYPH
COOLING EQUIPMENT
NYPH: Up and Running with PHPP
18
2021
bldgtyp | NYPH
Supply Air Heating? Sometimes…. Maybe…
bldgtyp | NYPH
NYPH: Up and Running with PHPP
19
2021
What About Supply Air Cooling?
bldgtyp | NYPH
Heating Load
Cooling Load
bldgtyp | NYPH
NYPH: Up and Running with PHPP
20
2021
Due to the relatively small ΔT (compared to heating) and the low flow rates of the ventilation system, supply-air cooling is very difficult to achieve in practice. This is especially true in climates with large dehumidification loads.
bldgtyp | NYPH
Air-Source Heat Pumps Can be used for heating and cooling, for many types of buildings. They do not GENERATE heat, but instead use the refrigeration cycle to MOVE (pump) heat. Outdoor Unit
Indoor Unit
bldgtyp | NYPH
NYPH: Up and Running with PHPP
21
2021
Many Form Factors
© Passive House Academy
bldgtyp | NYPH
Properly Sizing A Heat Pump for Residential Be Careful not to oversize, otherwise you can have humidity trouble.
bldgtyp | NYPH
NYPH: Up and Running with PHPP
22
2021
PHPP ‘Heat Pump Tool’ https://passivehouse.com/05_service/02_tools/02_tools.htm
bldgtyp | NYPH
NYPH: Up and Running with PHPP
23