English

Central ventilation systems with heat recovery have shown their limits especially within the context of building energy retrofit. The difficulties to install these systems in existing buildings, to find available space for devices, air ducts, silencers and fire dampers and to independently control the air flow in each room according to the real ventilation needs have led to an increasing market for decentralized ventilation devices.

The indoor climate in residential buildings is affected by the people that live in the house and their activities. One of the goals of a ventilation system is to prevent excess humidity in the house by removing part of the moisture. The moisture balance can however be distorted in winter with a low humidity in the house as a result.

Measurements were performed in a test room at SINTEF building and infrastructure, Oslo. The test room is 16 m2 and built according to NS-EN 442-2.  Measurements of various air flow rates (9 l/s, 18 l/s, 34 l/s and 50 l/s) and different supply air temperatures (2, 4, 6 and 10 degrees over room temperature) were performed. Tracer gas (SF6) measurements were performed to evaluate ventilation effectiveness and age of air in occupied zone.

An office building of the Fraunhofer Institute for Solar Energy systems (Fraunhofer ISE) in Freiburg was retrofitted in 2012 with an innovative concept based on technology integration in the façade. Prefabricated window modules integrating air inlets and outlets, façade integrated air ducts and a heat and moisture recovery ventilation device were implemented. A long term monitoring was set up including energy, temperature, CO2 and humidity measurements.

Demand controlled ventilation (DCV) considerably reduce the ventilation airflow rates and energy use compared to Constant Air Volume (CAV) systems. DCV in commercial buildings is probably a prerequisite to achieve ambitious energy-goal. However, evaluation of real energy use demonstrates that the energy saving potential is seldom met. DCV-based ventilation systems must become more reliable to close the gap between theoretical and real energy-performance.

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.