PR2014

Most existing non-residential buildings have Constant Air Volume (CAV) ventilation leading to over-ventilation in periods with low or no occupancy. Demand controlled ventilation (DCV) can considerably reduce the ventilation airflow rate and energy use for fans, heating and cooling compared to constant air volume (CAV) ventilation. There is a potentially enormous upcoming marked for converting from CAV to efficient DCV in existing commercial buildings.

The aim of improving air tightness of structures is to prevent the uncontrolled air leakages through structures. Built environments contain microbes, particulate and gaseous impurities but removing them is not always necessary. For example, an ageing building envelope commonly contains microbial impurities even when there is no obvious moisture damage. Air leaks convey impurities to indoors where they can lead to poor indoor air quality and associated health problems. Air leaks have also negative impact to energy efficiency and living comfort.

Improving the airtightness of housing is an issue that concerns the Chilean state. Building ordinances do not currently include any requirement to limit infiltration and its associated energy loads. This situation affects the energy and environmental performance of housing, and has economic and social consequences of great importance for inhabitants and the State. This text presents part of a research project commissioned by the Chilean Ministry of Housing and Public Works, with the aim of defining acceptable airtightness standards for buildings by territorial zone in Chile.

Many studies about photocatalytic oxidation (PCO) have been carried out in laboratories. They use an inert test chamber with ideal indoor conditions: a low volume, a controlled temperature and humidity, and a constant injection of one to five specific gases. The principal aim of this study was to implement, in a real test room (TR) of an experimental house, a titanium dioxide (TiO2) layer to quantify its efficiency.

This study presents a comparison of air leakage measurements collected recently (November 2013 to March 2014) with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007-2008. The purpose of the comparison is to determine if there are changes to the airtightness of building envelopes over time. Durability of building envelope is important to new homes that are increasingly built with improved levels of airtightness.

The ventilation required in order to maintain acceptable indoor hygiene standards results in a significant consumption of energy. Currently the Spanish regulations on indoor air quality (IAQ) require minimum rates for delivery-to and extraction-from the habitable rooms of residential buildings. These rates are not adjustable, so ventilation systems based on variable ventilation rates, are not normally deemed acceptable unless a comprehensive statement of compliance is provided, justifying the proposed ventilation solution.

Carbon dioxide included in exhaled breath is often used as a tracer gas when estimation of ventilation aspect in buildings with occupants is performed. Carbon dioxide produced by occupants is the key for the estimation. JIS A 1406 and ASTM D6245-12 refer personal carbon dioxide production rate. However JIS does not take into account personal attribute like as body height and weight. On the other hand, ASTM does not take into account gender difference and based on average westerner adult data.

Adopting natural ventilation as a retrofit strategy for cooling, due to the low impact nature of the installation, is attractive due to the cooling potential of untreated outdoor air for large periods of the extended cooling season, particularly in northern climates. In line with this it is important to characterise the performance of natural ventilation components in low energy buildings in successfully transferring the cooling potential of outdoor air to the occupied zone.