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U2 - LBNL-50248 ER - TY - JOUR T1 - A Comparison of the Power Law to Quadratic Formulations for Air Infiltration Calculations JF - Energy and Buildings Y1 - 1998/ SP - 293 EP - 299 A1 - Iain S. Walker A1 - David J. Wilson A1 - Max H. Sherman AB - Although the power law has been broadly accepted in measurement and air infiltration standards, and in many air infiltration calculation methods, the assumption that the power law is true over the range of pressures that a building envelope experiences has not been well documented. In this paper, we examine the validity of the power law through theoretical analysis, laboratory measurements of crack flow and detailed field tests of building envelopes. The results of the theoretical considerations, and field and laboratory measurements indicate that the power law is valid for low pressure building envelope leakage. VL - 27 U1 -2.3

U2 - LBNL-41447 ER - TY - JOUR T1 - Field Validation of Algebraic Equations for Stack and Wind Driven Air Infiltration Calculations JF - HVAC&R Research Y1 - 1998/ SP - 119 EP - 139 A1 - Iain S. Walker A1 - David J. Wilson AB - Explicit algebraic equations for calculation of wind and stack driven ventilation were developed by parametrically matching exact solutions to the flow equations for building envelopes. These separate wind and stack effect flow calculation procedures were incorporated in a simple natural ventilation model, AIM- 2, with empirical functions for superposition of wind and stack effect and for estimating wind shelter. The major improvements over previous simplified ventilation calculations are: a power law pressure-flow relationship is used to develop the flow equations form first principles, the furnace or fireplace flue is included as a separate leakage site and the model differentiates between houses with basements (or slab-on- grade) and crawlspaces. Over 3400 hours of measured ventilation rates from the test houses at the Alberta Home Heating Research Facility were used to validate the predictions of ventilation rates and to compare the AIM-2 predictions to those of other ventilation models. The AIM-2 model had bias and scatter errors of less than 15% for wind-dominated ventilation, and less than 7% for buoyancy ("stack-effect") dominated cases. VL - 4 U1 - 2.3 U2 - LBNL-42361 ER - TY - JOUR T1 - Field Validation of Equations for Stack and Wind Driven Air Infiltration Calculations JF - ASHRAE HVAC&R Research Journal Y1 - 1998/04// SP - 119 EP - 140 A1 - Iain S. Walker A1 - David J. Wilson VL - 4 IS - 2 ER - TY - JOUR T1 - A Wind Shadow Model for Air Infiltration Sheltering by Upwind Obstacles JF - ASHRAE HVAC&R Research Journal Y1 - 1996/ SP - 265 EP - 283 A1 - Iain S. Walker A1 - David J. Wilson A1 - Tom W. Forest AB - The wind shadow model has been developed to calculate the wind sheltering effects of upwind obstacles for air infiltration calculations. This effect must be determined for infiltration calculations because, in almost all situations, only the unobstructed mean wind speed is known for a building site. This model has adapted the theoretical calculation procedures developed for far wake centreline velocity deficit calculations to near field flows, where shelter has a significant effect. The model uses the concept of a wind shadow projected downstream by upwind buildings to determine the effect of wake velocity reduction on building surfaces. The turbulent nature of the wake is accounted for by "flapping" the wake over a range of wind directions. The effectiveness of this model in accounting for sheltering effects in infiltration calculations has been examined by comparing infiltration model predictions including the wind shadow model to measured data from a row of test houses. The measured data covered a wide range of wind speeds, wind directions and leakage distributions by using over five thousand hours of infiltration measurements from five houses. VL - 2 IS - 4 U1 - 2.3 ER - TY - Generic T1 - A Simple Calculation Method for Attic Ventilation Rates T2 - Proceedings of the 16th AIVC Conference Y1 - 1995/ SP - 221 EP - 232 A1 - Iain S. Walker A1 - Tom W. Forest A1 - David J. Wilson AB - The ventilation of an attic is critical in estimating heating and cooling loads for buildings because the air temperature in the attic is highly sensitive to ventilation rate. In addition, attic ventilation is an important parameter for determining moisture accumulation in attic spaces that can lead to structural damage and reduced insulation effectiveness. Historically, attic venting has been a common method for controlling attic temperature and moisture, but there have been no calculation techniques available to determine attic ventilation rates. Current practice is to use rules of thumb for estimating attic vent areas. Simple algebraic relationships are developed here, using functions fitted to an exact numerical solution for air flow through attic envelopes. This algebraic model (AVENT) was developed to be easy to use as diagnostic or design tool. Key factors included in the model are: climate (wind and stack effect), wind shelter, leakage distribution and total attic leakage. This paper validates the model predictions by comparing to measured data from two attics at the Alberta Home Heating Research Facility (AHHRF). Average errors for the model are about 15% compared to the measured ventilation rates. JF - Proceedings of the 16th AIVC Conference PB - Air Infiltration and Ventilation Centre, Coventry, Great Britain CY - Coventry, Great Britain VL - 1 U1 - 2.3 U2 - LBL-36879 ER - TY - Generic T1 - Practical Methods for Improving Estimates of Natural Ventilation Rates T2 - 15th AIVC Conference: The Role of Ventilation (Best Paper Award) Y1 - 1994/ SP - 517 EP - 526 A1 - Iain S. Walker A1 - David J. Wilson JF - 15th AIVC Conference: The Role of Ventilation (Best Paper Award) T3 - Proc. 15th AIVC Conference : The Role of Ventilation PB - Air Infiltration and Ventilation Centre CY - Coventry, U.K. VL - 1 ER - TY - JOUR T1 - Evaluating Models for Superposition of Wind and Stack Effects in Air Infiltration JF - Building and Environment Y1 - 1993/// SP - 201 EP - 210 A1 - Iain S. Walker A1 - David J. Wilson VL - 28 IS - 2 ER - TY - MGZN T1 - Infiltration Data From the Alberta Home Heating Research Facility Y1 - 1993/ A1 - David J. Wilson A1 - Iain S. Walker JF - AIVC Technical Note 41 ER - TY - Generic T1 - Feasibility of Passive Ventilation by Constant Area Vents to Maintain Indoor Air Quality in Houses T2 - Indoor Air Quality '92, ASHRAE/ACGIH/AIHA Conf. Y1 - 1992/10// A1 - David J. Wilson A1 - Iain S. Walker JF - Indoor Air Quality '92, ASHRAE/ACGIH/AIHA Conf. T3 - Proceedings Indoor Air Quality '92, ASHRAE/ACGIH/AIHA Conf., San Francisco, October 1992. CY - San Francisco, CA ER - TY - RPRT T1 - Passive Ventilation to Maintain Indoor Air Quality Y1 - 1991/ A1 - David J. Wilson A1 - Iain S. Walker JF - Report # 81 PB - University of Alberta Department of Mechanical Engineering ER - TY - Generic T1 - Wind Shelter Effects for a Row of Houses T2 - 12th AIVC Conference Y1 - 1991/ SP - 335 EP - 346 A1 - David J. Wilson A1 - Iain S. Walker JF - 12th AIVC Conference T3 - Proceedings 12th AIVC Conference PB - Air Infiltration and Ventilation Centre CY - Ottawa, Ontario, Canada VL - 1 ER - TY - RPRT T1 - The Alberta Infiltration Model, AIM - 2 Y1 - 1990/ A1 - Iain S. Walker A1 - David J. Wilson JF - Report #71. PB - University of Alberta Department of Mechanical Engineering CY - Edmonton ER - TY - Generic T1 - Combining Air Infiltration and Exhaust Ventilation T2 - Indoor Air '90, Y1 - 1990/07// SP - 467 EP - 472 A1 - David J. Wilson A1 - Iain S. Walker JF - Indoor Air '90, T3 - Proc. Indoor Air '90 PB - Indoor Air CY - Toronto, Canada ER - TY - MGZN T1 - Including Furnace Flue Leakage in a Simple Air Infiltration Model Y1 - 1990/ A1 - Iain S. Walker A1 - David J. Wilson JF - Air Infiltration Review VL - 11 IS - 4 ER - TY - JOUR T1 - Relating Actual and Effective Ventilation in Determining In-door Air Quality JF - Building and Environment Y1 - 1986/// SP - 135 EP - 144 A1 - Max H. Sherman A1 - David J. Wilson VL - 21 IS - 3/4 U2 - LBL 20424 ER - TY - JOUR T1 - Variability in Residential Air Leakage JF - Measured Air Leakage Performance of Buildings, (Trechsel/Lagus Ed.) Y1 - 1986/// SP - 348 EP - 364 A1 - Max H. Sherman A1 - David J. Wilson A1 - Darwin Kiel VL - STP:904 U2 - LBL-17587 ER - TY - JOUR T1 - Air Leakage Flow Correlations for Varying House Construction JF - ASHRAE Transactions Y1 - 1985/// A1 - Darwin Kiel A1 - David J. Wilson A1 - Max H. Sherman AB - Fan pressurization techniques are being employed by an increasingly large number of contractorsand auditors to determine the leakage characteristics of structures. In this study, a largedata base of flow exponents and flow coefficients are compiled to determine the degree ofcorrelation that exists between flow parameters. The resulting empirical relationships arethen used to determine the feasibility of predicting these flow parameters directly from asingle pressure difference test. On the basis of these correlations, a new pressureindependent tigh~ness parameter is proposed. VL - 91 IS - 1 U2 - LBL-18732 ER -