ASHRAE Journal - April 2010 - 23

obtained from NOAA for Michiana Regional Airport about 13 miles north of the crime scene for April 1989. For the period of interest, the outdoor dew point steadily dropped from a high of 52°F (11°C) (4 p.m. Saturday) to a low of 36°F (2°C) (1 p.m. Sunday). The time averaged dew point for that period was Natural Drying 42.1°F (6°C), the average wind speed was 8 mph (3.57 m/s), For the purposes of this study, natural drying is the process of and the low temperature was 41°F (5°C) (Table 1). evaporation of water from a wet surface without the interference Because the house was not equipped with a humidifier or an of artificial heating, cooling, wind or forced convection. This air conditioner, the amount of water in the indoor air is governed may also be called free convection. While there is an abun- by infiltration. While some amount of water is added to the air dance of literature on forced heat and mass transfer of wetted by showers, cooking and the like, these are very minor contribusurfaces, no helpful literature on the actual process of indoor tors, especially late at night in a house with no human activity. clothes drying, or the like, could be found; additionally, time The residence was built in 1975. The construction techniques did not permit a vast review of 1975 are such that the Temperature Dew Point Wind Speed of relevant literature as a trial house probably is of medium (°F) (°F) (Knots) could possibly occur in a few airtightness class. A medium Saturday, April 29,1989 weeks. An empirical approach class house surrounded by 4:00 p.m. 64 52 4 was selected early in the pro7.5 mph (3.35 m/s) wind has 7:00 p.m. 61 50 6 gram to determine the time approximately one complete 10:00 p.m. 55 45 10 required to dry a bathmat and air change every two hours.3 Sunday, April 30, 1989 washcloths in that particular Note that the average wind 1:00 a.m. 49 41 8 parsonage bathroom, on that speed was 8 mph (3.57 m/s) 4:00 a.m. 41 37 5 particular night. at the time of interest. 7:00 a.m. 42 38 6 Since the weather data is 10:00 a.m. 49 38 8 Indoor Space Conditions reported at the middle of 1:00 p.m. 53 36 9 Of critical importance to every three-hour period and determining the drying time of Table 1: Weather data for Michiana Regional Airport. the air is changed every two this process was estimating the space conditions for the bath- hours, the air in the house will have almost the same dew point room. The residence exterior doors and windows were closed as the reported outside air. The estimated indoor dew point when the crime was discovered. Additionally, the bathroom was was the outside air average of 42.1°F (6°C). However, as with an interior space, and its door was open to the hall. temperature, the exact dew point is not critical. Although there The space conditions (temperature and humidity) in the bath- is a hygroscopic flywheel in the house, the April dew point room were not recorded by investigators. However, the space average was 34°F (1°C). Using a dew point of 42.1°F (6°C) conditions of the bathroom can be estimated from knowledge was very conservative. of the structure and the weather data. The structure has a forced The space air condition of 72°F (22°C) and 42.1°F (6°C) air heating system, as was seen from the police video of the dew point will be used as the space condition of the bathroom floor diffuser in the bathroom. The air temperature and humidity during the period of interest and will be referred to as SBSC in the bathroom should have been nearly identical to the air in (South Bend Standard Conditions). the rest of the house, particularly as there was supposedly no activity in the house for 20 hours. Test Conditions and Data Correction The low temperatures for April 28, 29 and 30 were in the 40s Originally, the use of an environmental chamber to replicate and the furnace likely was enabled and operated by a thermostat the space conditions of the crime scene during the period to keep the occupants warm in the evening. Additionally, there of interest was considered. Air conditioning manufacturwere no comments on the police video tape as to the space being ers refer to these as psychrometric chambers. However, to uncomfortably hot or cold. The temperature limits for human prevent stratification, these chambers are deliberately windy. comfort for low humidity conditions2 during the winter are be- That windy condition would not accurately model the indoor tween 69°F and 76°F (21°C and 24°C). The space temperature conditions of a completely interior residential bathroom and was estimated to be 72°F (22°C), but as will be seen, the exact would cause the bathmat droplets and washcloth to dry at an temperature is not critical. artificially high rate. As the indoor dew point is overwhelmingly governed by the Testing was done in a residence and data corrected to anticioutdoor dew point, a certified copy of the weather data was pated space conditions of the bathroom (SBSC), as is done in
April	2010	 ASHRAE	Journal	 23

defense. Certainly, someone wetted these items. If someone else was proved to be in the parsonage during that 20-hour period, the guilt of the son would be at question. (A more detailed discussion of these events can be found in Reference 1.)



ASHRAE Journal - April 2010

Table of Contents for the Digital Edition of ASHRAE Journal - April 2010

ASHRAE Journal - April 2010
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
The Science of Evaporation is Key to Defense in Murder Trial
Selecting DOAS Equipment with Reserve Capacity
Technology Award Case Studies: Greening Hospitals
Technology Award Case Studies: Sustainable Remedy for Hospital
Building Sciences
Emerging Technologies
Technical Topics: Selecting Efficient Fans
Technical Topics: Dual-Capacity Heat Pumps
IAQ Applications
International Column
Classified Advertising
Advertisers Index
ASHRAE Journal - April 2010 - Intro
ASHRAE Journal - April 2010 - ASHRAE Journal - April 2010
ASHRAE Journal - April 2010 - Cover2
ASHRAE Journal - April 2010 - 1
ASHRAE Journal - April 2010 - 2
ASHRAE Journal - April 2010 - Contents
ASHRAE Journal - April 2010 - Commentary
ASHRAE Journal - April 2010 - 5
ASHRAE Journal - April 2010 - Industry News
ASHRAE Journal - April 2010 - 7
ASHRAE Journal - April 2010 - 8
ASHRAE Journal - April 2010 - 9
ASHRAE Journal - April 2010 - 10
ASHRAE Journal - April 2010 - 11
ASHRAE Journal - April 2010 - 12
ASHRAE Journal - April 2010 - 13
ASHRAE Journal - April 2010 - 14
ASHRAE Journal - April 2010 - 15
ASHRAE Journal - April 2010 - 16
ASHRAE Journal - April 2010 - 17
ASHRAE Journal - April 2010 - Letters
ASHRAE Journal - April 2010 - 19
ASHRAE Journal - April 2010 - Meetings and Shows
ASHRAE Journal - April 2010 - 21
ASHRAE Journal - April 2010 - The Science of Evaporation is Key to Defense in Murder Trial
ASHRAE Journal - April 2010 - 23
ASHRAE Journal - April 2010 - 24
ASHRAE Journal - April 2010 - 25
ASHRAE Journal - April 2010 - 26
ASHRAE Journal - April 2010 - 27
ASHRAE Journal - April 2010 - 28
ASHRAE Journal - April 2010 - 29
ASHRAE Journal - April 2010 - Selecting DOAS Equipment with Reserve Capacity
ASHRAE Journal - April 2010 - 31
ASHRAE Journal - April 2010 - 32
ASHRAE Journal - April 2010 - BRC1
ASHRAE Journal - April 2010 - BRC2
ASHRAE Journal - April 2010 - 33
ASHRAE Journal - April 2010 - 34
ASHRAE Journal - April 2010 - 35
ASHRAE Journal - April 2010 - 36
ASHRAE Journal - April 2010 - 37
ASHRAE Journal - April 2010 - 38
ASHRAE Journal - April 2010 - 39
ASHRAE Journal - April 2010 - 40
ASHRAE Journal - April 2010 - 41
ASHRAE Journal - April 2010 - Technology Award Case Studies: Greening Hospitals
ASHRAE Journal - April 2010 - 43
ASHRAE Journal - April 2010 - 44
ASHRAE Journal - April 2010 - 45
ASHRAE Journal - April 2010 - 46
ASHRAE Journal - April 2010 - 47
ASHRAE Journal - April 2010 - 48
ASHRAE Journal - April 2010 - 49
ASHRAE Journal - April 2010 - Technology Award Case Studies: Sustainable Remedy for Hospital
ASHRAE Journal - April 2010 - 51
ASHRAE Journal - April 2010 - 52
ASHRAE Journal - April 2010 - 53
ASHRAE Journal - April 2010 - Building Sciences
ASHRAE Journal - April 2010 - 55
ASHRAE Journal - April 2010 - 56
ASHRAE Journal - April 2010 - AP1
ASHRAE Journal - April 2010 - AP2
ASHRAE Journal - April 2010 - AP3
ASHRAE Journal - April 2010 - AP4
ASHRAE Journal - April 2010 - 57
ASHRAE Journal - April 2010 - 58
ASHRAE Journal - April 2010 - 59
ASHRAE Journal - April 2010 - Emerging Technologies
ASHRAE Journal - April 2010 - 61
ASHRAE Journal - April 2010 - 62
ASHRAE Journal - April 2010 - 63
ASHRAE Journal - April 2010 - Technical Topics: Selecting Efficient Fans
ASHRAE Journal - April 2010 - 65
ASHRAE Journal - April 2010 - Technical Topics: Dual-Capacity Heat Pumps
ASHRAE Journal - April 2010 - 67
ASHRAE Journal - April 2010 - 68
ASHRAE Journal - April 2010 - 69
ASHRAE Journal - April 2010 - IAQ Applications
ASHRAE Journal - April 2010 - 71
ASHRAE Journal - April 2010 - 72
ASHRAE Journal - April 2010 - 73
ASHRAE Journal - April 2010 - International Column
ASHRAE Journal - April 2010 - 75
ASHRAE Journal - April 2010 - 76
ASHRAE Journal - April 2010 - 77
ASHRAE Journal - April 2010 - 78
ASHRAE Journal - April 2010 - 79
ASHRAE Journal - April 2010 - 80
ASHRAE Journal - April 2010 - 81
ASHRAE Journal - April 2010 - 82
ASHRAE Journal - April 2010 - 83
ASHRAE Journal - April 2010 - 84
ASHRAE Journal - April 2010 - 85
ASHRAE Journal - April 2010 - Classified Advertising
ASHRAE Journal - April 2010 - 87
ASHRAE Journal - April 2010 - Advertisers Index
ASHRAE Journal - April 2010 - Cover3
ASHRAE Journal - April 2010 - Cover4
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