building envelope

States that 80% or more of infiltration is due to the many imperfections designed into the building envelopes. Discusses the problem and the role of ANSI/ASHRAE Standard 62-1999.

States that the design team must set goals in order to successfully achieve high-performance, low energy buildings. The energy design process can help to achieve the desired effect, beginning in the predesign phase and continuing through to commissioning and occupation. A good understanding of various strategies, the setting of aggressive energy targets and employing computer simulations all contribute to the process. After the building envelope has been optimised, the mechanical/electrical/control systems can be designed.

States that buildings in Saudi Arabia are often constructed without attention to the occupant discomfort caused by hot summer temperatures. Single-zone thermostats tend to limit comfort to the sun-side of office buildings, and there is also a possibility of asymmetrical radiation. Describes a pilot study conducted in a room in which airflows and temperatures were measured and then simulated using CFD techniques. Several factors were identified which contributed to the problem.

Discusses what benefits there may be in employing an effective quality assurance program for building envelope air barrier systems, and what elements it should include. Proposes a protocol for inspection and testing of building envelope air barrier systems. Cites literature to highlight how testing has been shown to improve a building's air permeance.

In situ measurements were compared with a numerical model to assess the effectiveness of the model for active envelopes as energy efficient building envelope solutions. There was good agreement for the mechanical flow active envelope, but not for the natural flow variant. States that taking into account the enthalpy change of the cavity air is essential for a correct evaluation of the energy efficiency of active envelopes.

Illustrates a procedure to optimise the building envelope during the early design stages, in respect to costs, construction and use and energy performance improvements. The tool is aimed at project authors and client. Of the tool's two linked modules, the first manages parameters for the project requirements, and the second, a graphics module, enables sketches and calculations for input to the first module.

Field measurements and numerical simulation were used to measure moisture transfer to the building envelope for a building with and without a vapour barrier. The results indicated that the vapour resistance of the barrier can be significantly below that provided by polyethylene, even in cold climates. States that moisture transfer from indoor air to the envelope can be seen as improving the indoor air quality by moderating the indoor humidity.

Postulates that figures for the energy load of a building affected by infiltration may be too high because the simple formula used does not account for heat recovery within the building envelope. In the study, sensible heat transfer was simulated with the used of CFD in typical envelopes. The results confirmed a possible overprediction of energy load up to 95% at low leakage rates.

The sessions in this conference covered: moisture control performance measurements; from the basement to the roof; moisture model inputs; wall design and building science; moisture model validation; wall performance; applied heat and moisture modelling; wall durability; whole buildings; fenestration practices; reducing foundation heat loss; roof design; green buildings; energy in buildings; building durability; fenestration principles; building performance; attics and roofs; indoor environment; low-slope roofs; mechanical systems; and workshops on a variety of topics.

The context of this work is the development of tools of thermal design adopted in the act of architectural design process, and the difficulty of architects and designers find when using these tools in the analysis of thermal performance of buildings, since this analysis requires specific knowledge. This paper aims to present a simplified method to be used in the preliminary phases of the architectural project process. This method obeys to expert rules which take into account an approach of thermal performance criteria.