ASHRAE Journal - May 2011 - 80

solar NZEB projEct
summer, Equinox House conditioning capacities are similarly reduced, however the hot humid summers in central Illinois result in Equinox House having a high latent load relative to its sensible load. Managing the latent load is one of the challenges in super-insulated, super-sealed homes. Notice that a significant number of days exist during the “swing” seasons (fall and spring) for both homes in which heating and dehumidification are required. A basement dehumidifier or the equivalent can be used to convert the latent heat of condensation into sensible heat. Figure 3 shows the location of the comfort conditioning system, located in a utility chase (attic) that is within the conditioned envelope of Equinox House. The comfort conditioning system installed in Equinox House is a small, air source heat pump that is incorporated into the fresh air ventilation system. The heat pump can exchange energy between the incoming fresh air and the outgoing exhaust air when it is beneficial to do so. Two 1,500 W electric heaters are used for supplementing the air source heat pump during times with low ambient air temperatures. The air source heat pump consists of a variable speed compressor. The nominal heating and cooling capacity of the unit is 2,000 W (6,900 Btu/h) with a compressor power of 400 W. In addition to the house conditioning system, as discussed in the April 2011 article on appliances, the heat pump water heater contributes approximately 2.5 kWh per day per person of cooling and dehumidification and the ventless heat pump dryer adds approximately 2.5 kWh per laundry load to the house. Cooking energy, lighting, refrigerator and other electrical appliances of lesser importance also contribute heating loads. Figure 4 shows the ventilation ductwork connected to the fresh air, exhaust air, supply air, and return air duct systems. The balanced ventilation system consists of two “duct” fans with a flow of 100 L/s (210 cfm) that provides fresh air to the house for one hour out of every three hours. The fans require 70 W each, with the energy from one fan added to the supply airstream and the energy from the other fan exhausted to the outside. The additional two hours of the duty cycle can be used for house conditioning when required, with the ventilation system in a “recirculation” mode rather than fresh air mode. When outside air is “nicer” than inside air, the system operates in “free” conditioning mode, leaving the heat pump off while bringing in fresh air to condition the house; equivalent to opening the windows in the house. The two additional hours also allow for increased fresh air ventilation during periods of high occupancy levels. The ventilation system is designed such that fresh air is supplied to the “living” areas of the house (living room and bedrooms), and return air to be exhausted from the house is pulled from the kitchen, laundry room and bathrooms. In this manner, the house is “purged” by the airflow. The ventilation system is designed such that wireless sensors in the bathroom light circuits change the ventilation system to fresh air mode when bathrooms are occupied. Figure 5 shows temperature collected at three interior locations (living room, master bedroom and utility attic space) and outdoor ambient reported by a local weather service from
80 ASHRAE Journal
Dec., Jan., Feb. 2,500
(constructed Within 10 Years)

Mar., Apr., May. conventional Home

Jun., Jul., Aug.

Sept., Oct., Nov. Cooling and Dehumidification

2,000 1,500 1,000 500 0 –500 –1,000 –15,000

•	 2,370 ft2 Single Story •	 UA = 456 Btu/h ·°F •	 % Glass = 0.05 (Window to Floor Area) •	 Infiltration	=	2,000	cfm	at	0.2	in.	w.c. •	 Vented Crawlspace Heating and Dehumidification

Qlatent (W)

Cooling and Humidification Heating and Humidification –10,000 –5,000 Qsensible (W) 0 5,000

2,500 2,000 1,500 1,000 500 0 –500 –1,000 –15,000 Equinox House •	 2,100 ft2 •	 UA = 190 Btu/h ·°F •	 % Glass = 0.076 (Window to Floor Area) •	 Infiltration	=	260	cfm	at	0.2	in.	w.c. •	 Slab on Grade Heating and Dehumidification

Cooling and Dehumidification

Qlatent (W)

Heating and Humidification –10,000 –5,000 Qsensible (W) 0

Cooling and Humidification 5,000

Figure 1 (top): Conventional house daily average latent and sensible conditioning capacity requirements to maintain comfort conditions. Figure 2 (bottom): Equinox House daily average latent and sensible conditioning capacity requirements to maintain comfort conditions. January to early March 2011. At the end of January is the time period when Equinox House was unoccupied during the ASHRAE Winter Conference. For three days, the interior temperature declined. Comfort conditioning systems were activated after three days to observe the dynamics of moving the house back to comfort conditions. The temperatures shown for the master bedroom, living room and attic areas are quite close in temperature without any discernable temperature variations as one moves throughout the house. The average temperature level in the house has been maintained in the 19°C to 20°C (66°F to 68°F) range. Figure 6 shows the humidity ratio for the same time period in Equinox House. The associated relative humidity level is in the
ashrae.org May 2011



ASHRAE Journal - May 2011

Table of Contents for the Digital Edition of ASHRAE Journal - May 2011

ASHRAE Journal - May 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Seismic Restraint
Plug Load Design Factors
Technology Award Case Studies:
State-of-Art School
Green School Lab
Eco-Friendly, Affordable, School
Building Sciences
Special Section
InfoCenter
Solar NZEB Project
Emerging Technologies
IAQ Applications
Washington Report
International Column
Products
People
Classified Advertising
Advertisers Index
ASHRAE Journal - May 2011 - Intro
ASHRAE Journal - May 2011 - ASHRAE Journal - May 2011
ASHRAE Journal - May 2011 - Cover2
ASHRAE Journal - May 2011 - 1
ASHRAE Journal - May 2011 - 2
ASHRAE Journal - May 2011 - Contents
ASHRAE Journal - May 2011 - Commentary
ASHRAE Journal - May 2011 - 5
ASHRAE Journal - May 2011 - Industry News
ASHRAE Journal - May 2011 - 7
ASHRAE Journal - May 2011 - 8
ASHRAE Journal - May 2011 - 9
ASHRAE Journal - May 2011 - 10
ASHRAE Journal - May 2011 - 11
ASHRAE Journal - May 2011 - 12
ASHRAE Journal - May 2011 - 13
ASHRAE Journal - May 2011 - Letters
ASHRAE Journal - May 2011 - 15
ASHRAE Journal - May 2011 - 16
ASHRAE Journal - May 2011 - 16a
ASHRAE Journal - May 2011 - 16b
ASHRAE Journal - May 2011 - 17
ASHRAE Journal - May 2011 - Meetings and Shows
ASHRAE Journal - May 2011 - 19
ASHRAE Journal - May 2011 - Seismic Restraint
ASHRAE Journal - May 2011 - 21
ASHRAE Journal - May 2011 - 22
ASHRAE Journal - May 2011 - 23
ASHRAE Journal - May 2011 - 24
ASHRAE Journal - May 2011 - 25
ASHRAE Journal - May 2011 - 26
ASHRAE Journal - May 2011 - 27
ASHRAE Journal - May 2011 - 28
ASHRAE Journal - May 2011 - 29
ASHRAE Journal - May 2011 - Plug Load Design Factors
ASHRAE Journal - May 2011 - 31
ASHRAE Journal - May 2011 - 32
ASHRAE Journal - May 2011 - 33
ASHRAE Journal - May 2011 - 34
ASHRAE Journal - May 2011 - 35
ASHRAE Journal - May 2011 - State-of-Art School
ASHRAE Journal - May 2011 - 37
ASHRAE Journal - May 2011 - 38
ASHRAE Journal - May 2011 - 39
ASHRAE Journal - May 2011 - 40
ASHRAE Journal - May 2011 - 41
ASHRAE Journal - May 2011 - 42
ASHRAE Journal - May 2011 - 43
ASHRAE Journal - May 2011 - Green School Lab
ASHRAE Journal - May 2011 - 45
ASHRAE Journal - May 2011 - 46
ASHRAE Journal - May 2011 - 47
ASHRAE Journal - May 2011 - 48
ASHRAE Journal - May 2011 - 49
ASHRAE Journal - May 2011 - 50
ASHRAE Journal - May 2011 - 51
ASHRAE Journal - May 2011 - Eco-Friendly, Affordable, School
ASHRAE Journal - May 2011 - 53
ASHRAE Journal - May 2011 - 54
ASHRAE Journal - May 2011 - 55
ASHRAE Journal - May 2011 - 56
ASHRAE Journal - May 2011 - 57
ASHRAE Journal - May 2011 - Building Sciences
ASHRAE Journal - May 2011 - 59
ASHRAE Journal - May 2011 - 60
ASHRAE Journal - May 2011 - 61
ASHRAE Journal - May 2011 - 62
ASHRAE Journal - May 2011 - 63
ASHRAE Journal - May 2011 - 64
ASHRAE Journal - May 2011 - 65
ASHRAE Journal - May 2011 - 66
ASHRAE Journal - May 2011 - 67
ASHRAE Journal - May 2011 - InfoCenter
ASHRAE Journal - May 2011 - 69
ASHRAE Journal - May 2011 - 70
ASHRAE Journal - May 2011 - 71
ASHRAE Journal - May 2011 - 72
ASHRAE Journal - May 2011 - 73
ASHRAE Journal - May 2011 - 74
ASHRAE Journal - May 2011 - 75
ASHRAE Journal - May 2011 - 76
ASHRAE Journal - May 2011 - 77
ASHRAE Journal - May 2011 - Solar NZEB Project
ASHRAE Journal - May 2011 - 79
ASHRAE Journal - May 2011 - 80
ASHRAE Journal - May 2011 - 81
ASHRAE Journal - May 2011 - 82
ASHRAE Journal - May 2011 - 83
ASHRAE Journal - May 2011 - 84
ASHRAE Journal - May 2011 - 85
ASHRAE Journal - May 2011 - 86
ASHRAE Journal - May 2011 - 87
ASHRAE Journal - May 2011 - 88
ASHRAE Journal - May 2011 - 89
ASHRAE Journal - May 2011 - Emerging Technologies
ASHRAE Journal - May 2011 - 91
ASHRAE Journal - May 2011 - 92
ASHRAE Journal - May 2011 - 93
ASHRAE Journal - May 2011 - 94
ASHRAE Journal - May 2011 - 95
ASHRAE Journal - May 2011 - IAQ Applications
ASHRAE Journal - May 2011 - 97
ASHRAE Journal - May 2011 - 98
ASHRAE Journal - May 2011 - 99
ASHRAE Journal - May 2011 - 100
ASHRAE Journal - May 2011 - 101
ASHRAE Journal - May 2011 - Washington Report
ASHRAE Journal - May 2011 - 103
ASHRAE Journal - May 2011 - International Column
ASHRAE Journal - May 2011 - 105
ASHRAE Journal - May 2011 - 106
ASHRAE Journal - May 2011 - Products
ASHRAE Journal - May 2011 - 108
ASHRAE Journal - May 2011 - People
ASHRAE Journal - May 2011 - Classified Advertising
ASHRAE Journal - May 2011 - 111
ASHRAE Journal - May 2011 - Advertisers Index
ASHRAE Journal - May 2011 - Cover3
ASHRAE Journal - May 2011 - Cover4
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