El Diasty, R., P. Fazio and I. Budaiwi
1992
Energy and Buildings, 19, pp. 61-73
Indoor air humidity behaviour within an enclosure has been mathematically modebed. A linear differential equation is used to describe the response of indoor air humidity to different moisture transport processes within the space. The modelled processes include: moisture absorption/desorption, surface condensation, air movement across enclosure boundaries, indoor evaporation, and indoor moisture generation. By using a discrete time step, nonlinear processes, such as surface condensation, can be assumed linear within the time interval. The differential equation is solved as part of a comprehensive numerical formulation through which the behaviour of moisture transport process and its contribution to indoor humidity dynamics are modeled. A theoretical study of indoor air hun-tidity response to different moisture transport processes has revealed the importance of the involved processes in determining indoor air humiditybehaviour. The relative influence of a particular process depends on its time constant, its interaction with other processes, and the continuity of the process. In addition, the impact of a given moisture transport process will also depend on the building physical and functional characteristics, as well as the prevailing outdoor environmental conditions.
References
[8,9] The relationship between indoor humidity and air leakage and ventilation has been modelled to determine the effect of air exchange rate on indoor moisture level and to ezxamine the effect of other parameters, such as occupancy, building characteristics and external environmental prarmeters. Most of these parameters can have a significant impact on indoor humidity, esp. at a lower air exchange rate.
[16]: absorption/desorption process is modelled
[13, 19,20] models for indoor humidity calculations.
1 N. B. Hutcheon, Humidityin Canadian buildings, CAYL Build Digest, 137 (2) (1973) 1.1-1.4.
2 N. B. Hutcheon, HurrLidified buildings, CaiL Build Digest, 137 (2) (1973) 42.1-42.4.
3 A. T. Hanson, Moisture problems in houses, Can. Build Digest, 231 (1984).
4 K. M. Kelly, Indoor moisture effects on structure, comfort, energy, consumption, and health, Proc. ASLU?AEIDOE Conf. Thermal Perforntance of The Exterior Envelope of Build-i,ngs H, 1982, Las Vegas, IVV, pp. 1007-1032.
5 H. J. Hirning, L. P. Vogal and S. W. Handy, Energy con-servation in homes causes excess moisture problems, Proc. Winter Meeting Am. Soc. Agricultural Engineering, 1982, Chicago, LL, 1982, pp. 1-8.
6 P. R. Achenback, Moisture management in buildings, Proc. Symp. Air Infiltration, Ventilation and Moisture Transfer, Fort Worth, YX, Building Thermal Envelope Coordinating Council, 1986, pp. 73-81.
7 D. Kent, 0. Handegord and R. Robson, Study of humidity variations in Canadian buildings, ASHRAE 7~-am., 72 (2) (1966) 1.1-1.7.
8 G. A. Tsongas, The effect of building air leakage and ven-tilation on indoor relative humidity, Synib. Air Infilatration, Ventilation and Moisture 7'rarsfer, Fo?t Wo7lh, YX, Build-ing Thermal Envelope Coordinating Council, 1986, pp. 286-291
9 K. M. Lethepykan3 Room air moisture content: dynamic effect of ventilationand vapour generation, Build. Sci. Engr. Res. TechnoL, 9 (2) (1988) 49-52.
10 M. G. Davies, Computing the rate of superficial and interstitial condensation, Build. Sci., 8 (1973) 97-104.
11 M. G. Davies, Estimation of loss of water vapour from an enclosure, Build. Sci., 10 (1975) 185-188.
12 R. El-Diasty and 1. Budaiwi, External condensation on win-dows, Constr. Build Mat., 3 (3) (1989) 135-139.
13 T. Kusuda, Indoor humidity calculations, ASHRAE 7~-aws., 89 (2) (1983) 728-740.
14 P. C. Martin and J. D. Verchoor, Cyclical moisture desorption/ absorption by building construction and furnishing materials, Proc. Symp. Air Infiltratzon, Ventilation and Moisture
7'ra,nsfer, Fort Worth, 7X, Building Thermal Envelope Co-ordinating Council, 1986, pp. 59-69.
15 P. W. Fairey and A. A. Kerestecioglue, Dynamic modelling of combined thermal and moisture transport in buildings: effect of cooling loads and space conditionsJASBRAE Trans., 91 (2) (1985) 461-472.
16 J. D. Mfller, Development and validation of a moisture mass balance model for predicting residential cooling energy consumption, ASHRAE 7'rans., 90 (2) (1984) 275-292.
17 C. IsettiJ L. I4aurenti and A. PonticieRo, Predicting vapour content of indoor air and latent loads for air-conditioned envirorunent: effect of moisture storage capacity of the walls, Energy Build., 12 (1988) 141-148.
18 A. Kerestecioglue, M. Swan-d and A. Kamel, Theoretical and computational investigation of simultaneous heat and mois-ture transfer in buildings: 'Effective Penetration Depth' the-ory, ASHRAE 7'rans., 96 (1) (1990) 447-454.
19 C. G. Barringer and C. A. McGugan, Development of a dynamic model for simulating indoor air temperature and hurndiity, ASHRAE Trans., 95 (1989) 449-460.
20 A. TenWolde, A mathematical model for indoor humidity in houses during winter, Proc. Symp. Air Infiltration, Ven-tilation and Moisture 7~-ansfL-r, Fort Worth, 7X, Building Thermal Envelope Coordinating Council, 1986, pp. 4-32.
21 M. J. Cunningham, A new analytical approach to the long term behaviour of moisture concentration in building cavities - 1. Non-condensing cavity, Build. Environ., 18 (3) (1983) 109-116.
22 M. J. CunninghamJ A new analytical approach to the long term behaviour of moisture concentration in building cavities - Il. Condensing cavity, Build., Environ., 18 (3) (1983) 117-124.
23 M. J. Cunningham, Further analytical study of cavity moisture concentration, Build. Environ., 19 (1) (1984) 21-29.
24 E. Kreyszig, Advanced Engineering Mathematics, Wiley & Sons Inc., New York, 5th edn., 1983. |