Transient Interaction of Buildings with HVAC Systems— Updating the State of the Art

Abstract

This paper reviews work that has led to the development of a number of multi-zonal airflow models (network models). At present, the network analysis and perturbation methods cannot be used to solve the interstitial flow, pressure and resistance regimes. Network analysis and perturbation may suggest that such flows exist, but the complexity and workmanship dependence of the interstitial flow, pressure and resistance regime requires direct measurement. In other words, at present, the boundary conditions of the interstitial regime can be defined analytically using traditional methods, but the pressures and flows within the interstitial spaces cannot be predicted with certainty using analytical means.Difficulties in obtaining the detailed information on mechanical systems and the leakage areas of building assemblies make the traditional approach of measuring airflows and constructing models using leakage areas impractical for diagnostic purposes. Additionally, a pressure difference across an assembly alone, where interstitial pressures are not considered, is not enough to describe performance of the building envelope. The interstitial air pressures are usually small and until recently have been beyond measurement.Research on building envelope durability and indoor air quality has shown the significance of these small, but persisting interstitial air pressure fields. To enhance the capability of network models, a relational model was developed. This approach permits the measured building air pressure field to be used with the network analysis. Furthermore, the response of the analytical model is calibrated by comparing the effect of a specific perturbation on both the building air pressure field and the analytical model. This paper is written in two parts, the first reviewing issues in prediction of airflow in the buildings and building envelope, the second analyzing the actual data of measured pressure response of buildings. sake of clarity. When some relations are deemed less important than the others,

Integrated Methodology for Evaluation of Energy Performance of the Building Enclosures — Part 1: Test Program Development

“…Only recently in Scandinavia and North America the focus shifted to frame walls and included effects of air flow. It was found that air flows carry more moisture than water vapor diffusion, and that air, in a manner similar to sound transmission, flowing across and along building partitions, may connect seemingly separate regions of the building (Lstiburek, 2000;Lstiburek et al, 2000 and2002). Furthermore, moisture carried by air is a major factor affecting durability of building materials.…”

Is there an optimum range of airtightness for a building?

“…Measured directly on a section of the envelope, for example, using a box attached to the wall with window; Evaluated from multizonal network models and airflow perturbations (Lstiburek, 1998;Lstiburek et al, 2000Lstiburek et al, , 2002 or by similar method to separate the section from the surrounding space.…”

“…The effect of pathways created by external cavities and interconnected internal cavities communicating with HVAC systems on performance of building systems is often neglected (Figure 4). The significance of these elements has been illustrated in the few examples selected from case studies (Lstiburek, 1995, 2002, Lstiburek et al, 2000. Some other cases listed by Lstiburek (1998) are as follows: A facility located in a cold climate with inadequate provision for return air.…”

A concept of integrated environmental approach for building upgrades and new construction: Part 1—setting the stage

“…Energy+) allow inclusion of two- or three-dimensional model segments, one does not use this facility for inclusion of the HT modeling as a subset of energy modeling. Despite many research articles (Bomberg and Thorsell, 2008; Kosny et al, 2007; Lstiburek, 1999; Lstiburek et al, 2000, 2002; Said et al, 1997; Tamura, 1975; Tamura et al, 1974; Tamura and Wilson, 1963, 1966, 1967; Thorsell and Bomberg, 2008, 2011) highlighting effects of air and moisture on energy calculations with exception of some discussed in International Energy Agency (IEA) Annex 41, the whole-building energy models do not include effects of air and moisture transfer through walls.…”