Heat recovery in building envelopes

Infiltration has traditionally been assumed to contribute to the energy load of a building by an amount equal to the product of the infiltration flow rate and the enthalpy difference between inside and outside. Some studies have indicated that application of such a simple formula may produce an unreasonably high contribution because of heat recovery within the building envelope. The major objective of this study was to provide an improved prediction of the energy load due to infiltration by introducing a correction factor that multiplies the expression for the conventional load.

Dynamic buffer zone - Controlling moisture and heat flow

The building envelope is primarily an environmental separator, which allows indoor spaces to bemaintained at different conditions from the outside environment. Intentional humidification during the heating season is a common practice in cold climates. Moisture escaping from a humidified building due to air leakage through flaws in the air barrier system can negatively affect the durability of the building envelope.

Building envelope, duct leakage and HVAC system performance in HUD-code manufactured homes

Between 200,000 to 300,000 manufactured homes are built to the US Department of Housing and Urban Development’s Manufactured Home Construction and Safety Standards (MHCSS) in the US each year. This paper compares building envelope, duct leakage and HVAC s

Computer simulation of thermal impact of air infiltration through multilayered exterior walls

Convective air circulation occurring through wall layers is frequently observed in building envelopes. Significant thermal coupling can take place between the incoming cold/warm air and the wall structure, thereby modifying the thermal performances of the envelope. This paper presents an unsteady threedimensional numerical heat and air transfer model, which was developed to

The hygrothermal behaviour of rooms : combining thermal building simulation and hygrothermal envelope calculation

The hygrothermal behavior of a building component exposed to weather is an important aspect of the overall performance of a building. Today the hygric transport phenomena through a building envelope are well understood and a realistic assessment of all relevant effects can be carried out by one of the numerous models and computer programs, that have been developed in different countries over the last years. The calculation of the hygrothermal performance of a part of the envelope is state-of-the-art, but until now, the total behaviour of the actual whole building is not accounted for.

Approche de l'évaluation de l'influence des transferts aérauliques dans les parois sur la performance thermique de l'enveloppe

Generally the calculation methods ignore the interaction of air leakage and heat conduction in building envelope. The aim of this paper is to explore the different approaches that may be used to evaluate the energy impact of air infiltration through building walls and to compare those results with calculations done using the current method calculation.

Nondimensional methods for natural ventilation design

That paper deals with the use of nondimensioanl graphs for designing the envelopes of naturally ventilated buildings. The graphs can be generated from theoretical models or from experimental data via a direct measurment of ventilation rates in a wind tunnel model.
Examples of graphs are given: they cover conventional design conditions and off-design conditions.

Building airtightness : how tight is tight enough ?

The author explains that too tight building envelopes can cause bad operation of atmosperically vented combustion systems (e.g. gas water heaters) in case of of unintended depressurization of the building, for example with large exhaust fans and dirt filters. He considers that airtightness requirements of standards are often too severe. He proposes a building airtightness of 2 to 6 air changes per hour at 50 Pa for warm climates and 1.5 to 4 for cold climates, buildings with atmospherically vented combustion appliances being at the high end of the range or higher.

Energy performance assessment of single storey multiple-skin facades

Multiple-skin facades were studied by means of experiments and numerical simulations. Experimental work was done on naturally and mechanically ventilated single storey multiple skin facades. Field experiments showed that good design and excellent workmanship are of crucial importance to obtain the desired performance. The measurements enables an insight into the complex nature of the airflow in naturally ventilated cavities. Measurements on a controlled experimental set-up provided data to develop and validate a numerical model. This model was then implemented in an energy simulation tool.

European research project Solvent : development of a ventilated solar screen glazing system

The Solvent window was developed to improve visual and thermal comfort in sunny conditions. The glazing system realizes the conversion of short wave solar radiation to convective heat and long wave radiation.