AIVC - Air Infiltration and Ventilation Centre

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Assessing the energy use and IAQ of various HVAC systems during the early design stage

The early design stage of a building is decisive for describing the concept of the HVAC system. Designers and practitioners can adjust and optimize the design during this stage as it provides them with enough resilience to adapt new changes. In practice, a well-defined optimization process is essentially required in order to achieve the project’s goals within a reasonable time span. These goals vary from one project to another, and sometimes they require a comprehensive study to identify the factual and stochastic parameters and their impact on the design.

A review of the performance indicators of night-time ventilation

Night-time ventilation is a natural cooling technology, in which cold ambient air is used to cool indoor spaces. This literature review analyses how recent studies have defined the effectiveness or efficiency of night-time ventilation. Most studies used the similar indicators related to heat removal, energy saving, cooling demand reduction, and thermal comfort. However, there were significant differences between the definitions of performance of night-time ventilation, both in terms of criteria of judgement and methods of analysis.

Demand controlled ventilation: relevance of humidity based detection systems for the control of ventilation in the spaces occupied by persons

Design of ventilation systems in Belgium is currently based on the Belgian Standard NBN D 50-001:1991. This regulation is more than 25 years old, and is not anymore suited to new technologies developed in the frame of increasing energy performance of buildings and its associated ventilation systems. This standard defines four classic ventilation systems, going from A (natural ventilation) to D (double-flux ventilation eventually with heat recovery). One of its main shortcomings is that it does not consider demand controlled ventilation (DCV) systems.

Rethinking Occupancy-Based Ventilation Controls

Traditionally, occupancy-based ventilation controls have only ventilated when occupants are present – usually based on measurements of CO2 and/or humidity.  These indictors may be fine for pollutants released directly by occupants, such as bioeffluents, or by their activities, such as cooking and cleaning. However, they do not account for pollutants not associated with occupancy, such as formaldehyde from building materials and furnishings.

A review of performance-based approaches to residential smart ventilation

In order to better address energy and indoor air quality issues, ventilation needs to become smarter. A key smart ventilation concept is to use controls to ventilate more at times it provides either an energy or IAQ advantage (or both) and less when it provides a disadvantage. This would be done in a manner that provides improved home energy and IAQ performance, relative to a “dumb” base case. This paper highlights that a favourable context exists in many countries, with regulations and standards proposing “performance-based approaches”.

Olfactory adaptation model based on change of odor threshold using impulse response function

It is well known that the olfactory sensitivity changes with exposure time and concentration of odor under continuous exposure to odor in the air. This decrease of odorous sensitivity, the increase of odorous threshold in other words due to continuous exposure to odor is called olfactory adaptation. 

Impact of construction stages on Indoor Air Quality

Since the turn of the century, alarming data produced by the Indoor Air Quality Observatory (OQAI) have led to changes in French legislation, including, most notably, the introduction of compulsory labelling for construction products (decree no. 2011-321 of 23 March 2011).

Accuracy Improvement for Estimating Indoor Carbon Dioxide Concentration Produced by Occupants

Carbon dioxide included in exhaled breath is often used as a tracer gas when estimation of ventilation aspect in buildings with occupants is performed. Indoor carbon dioxide concentration is also adopted evaluation of ventilation commonly. It is needed for these investigations to grasp occupants’ carbon dioxide production rate accurately. 

Thamesmead Condensation, Damp and Mould Strategy. The use of smart thermostats to assess ventilation interventions with demand controlled ventilation

An implementation of a Condensation, Damp and Mould (CD&M) Strategy for the Thamesmead estate in south-east London Targeting 2000 homes. The evidence-based strategy is designed to manage CD&M systematically and focus on homes that will not be refurbished or replaced for some time. CD&M risk assessments and surveys are used to identify homes for a range of interventions, including energy advice, smart heating controllers and demand-controlled mechanical extract ventilation, in various combinations.

A Stochastic Approach to Estimate Uncertainty in Pollutant Concentrations in an Archetypal Chilean House

As policy makers strive to reduce the energy demands of houses by reducing infiltration rates, an unintended consequence could be a fall in the quality of indoor air with corresponding negative health effects at a population scale. Measuring pollutant concentrations in-situ is difficult, expensive, invasive, and time consuming and so the simulation of indoor conditions, using representative models of a housing stock, is a more common method of investigation.