Overview of methods to analyse dynamic data

This book gives an overview of existing data analysis methods to analyse the dynamic data obtained from full scale testing, with their advantages and drawbacks. The overview of full scale testing and dynamic data analysis is limited to energy performance characterization of either building components or whole buildings. The methods range from averaging and regression methods to dynamic approaches based on system identification techniques. These methods are discussed in relation to their application in following in situ measurements: -measurement of thermal transmittance of building components based on heat flux meters; -measurement of thermal and solar transmittance of building components tested in outdoor calorimetric test cells; -measurement of heat transfer coefficient and solar aperture of whole buildings based on co-heating or transient heating tests; -characterisation of the energy performance of whole buildings based on energy use monitoring

In-situ U-value-measurements of wood frame roofs: analysis of deviations between measured and design performance

The hygrothermal performance of various lightweight sloped roof designs was monitored in the KULeuven VLIET testbuilding for 2 years (Janssens et al. 1998). One of the aims of the investigation was to evaluate whether the design U-value of 0.18 W/m²K was effectively met in practice. For this reason 3 heatflux transducers were installed at the inside surface of each component together with a number of thermocouples at the surfaces of the composing material layers. The U-value was derived from the measurements by averageing the collected data on a daily basis. The observed deviations between the measured and design U-values are analysed and explained by quantifying the inconsistencies between the assumptions for the calculation of the design thermal performance and the conditions of the in-situ measurement. The following causes of deviations are analysed in detail, and related to the position of the heat flux transducer on the test components: (1) heat transport affected by wind-washing in the roofs, (2) 2-dimensional heat flow through framing elements in the roof

Analysis of the influence of ventilation rate on sleep pattern

In this paper, the results from a field study on the influence of ventilation rate on the sleep pattern are presented. The testgroup was asked to sleep in their normal sleeping environment (student dorms) in order to cause as little disruption in the normal pattern as possible. For the same reason, actigraphy was used to measure sleep patterns since this is one of the least disturbing measurement techniques available. The student dorms were selected as a location because all rooms are identical and basic conditions are therefore very similar for all the participants in the study. The participants were also asked to fill out a number of questionnaires to determine their general attitude towards sleep and to get an idea of their subjective appreciation of the sleep quality experienced over the test period. The results show only a very small effect of the ventilation rate on the sleep pattern

Evaluation of a prescriptive ventilation standard with regard to 3 different performance indicators

In this paper, the performance of Belgian building code compliant residential ventilation systems is evaluated on multiple performance indicators: occupant exposure to bio-effluents, occupant exposure to other use-related pollutants (odours) and occupant exposure to building material emissions. The fitness of the proposed criteria in this context is then discussed in a broader context and this information is then used to interpret the fitness of the code prescriptions as design criteria for performant ventilation systems

A simple airlfow path approach to sizing natural ventilation systems in a code context

Most of the existing ventilation standards are drafted in a rather prescriptive way. Growing focus on the implementation of rational energy use however, introduces an urgent need for more performance-based criteria. Optimization of energy consumption obviously encompasses minimization of ventilation airflow rates. Comfort, on the other hand, should not be reduced because of these actions. To implement this in a legal figure, one can appeal to the principle of equivalence. This principle states that all systems achieving equivalent performance to that of the systems described in the standard are acceptable. Better yet, a new standard can be devised, imposing a reference performance rather than a reference system. This avoids all discussion about the way the reference system’s performance should be interpreted. Nevertheless, practical implementation of a standard will require the definition of sizing guidelines for design purposes. The method presented in this paper is a simplified approximation of the airflow network in a building. It is conceived as a sizing guideline for natural ventilation systems in the context of a national ventilation standard. Supply, internal and exhaust resistances are the main parameters, next to overall building airtightness. These parameters are system independent and allow to describe a large scale of possible buildings. Five different dwellings, with different typologies, representative for the Flemish building stock, were evaluated for this purpose. The predicted airflow and indoor air quality are compared to that predicted by a detailed multi-zone model and acceptable agreement is found. This yields the conclusion that, for the implementation of a performance-based ventilation standard, straight forward calculation methods for sizing guidelines can be incorporated in the standard

Bedroom indoor air comfort : a critical analysis

The criteria that are currently used for the assessment of Indoor Air Quality in a residential context were developed in the ‘80s and relate to comfort during occupancy. More than half the time at home however, is spent in the bedroom. There is no strong indication that the criteria that are traditionally used to assess Indoor Air Quality also relate to the level of comfort while asleep. Moreover, analysis of the results of a performance assessment of frequently used residential ventilation systems based on these traditional criteria, shows that they are dominated by the pollution level in the bedrooms

Turbulent mixed convection in an enclosure with different inlet and outlet configurations

Given the large impact of the building sector on the final energy demand, special interest lays in passive cooling techniques, such as night ventilation. Unfortunately, a lack of understanding concerning the coupling between the ventilation air and the thermal mass by night stands its widespread application in the way. Therefore, the authors of this paper investigate by computational fluid dynamics turbulent mixed convection cooling in a rectangular enclosure – resembling a night ventilated landscape office. Based on the 2D Annex 20 test case, four different orientations of the inlet and outlet are considered while varying the Archimedes number – ranging from forced to mixed convection. Also the location of thermally massive elements is varied. Locating the inlet and outlet at the top of the room induces the highest convective heat transfer. Meanwhile, locating the thermal mass at the floor has more potential than at the ceiling

Passive house ventilation strategies: demand control?

Since insulation levels in a passive house context are very high, energy losses trough ventilation are of relatively high importance in the total energy balance of a passive house concept. Although fully mechanical ventilation systems are at the core of the this concept, enabling both regeneration and cheap space heating, it can still be optimized. With demand controlled systems, excess ventilation can be minimized, thus reducing both redundant ventilation losses and the accompanying electrical loads. This paper reviews the possibilities for a performance based optimization of ventilation systems for passive houses within the context of the Belgian legislatio