ventilation

Many studies reported that there were insufficient ventilation and excessive CO2 concentration in air-conditioned residential buildings, but few solutions were provided. This study first investigated the performance of three possible ventilation strategies of air-conditioned residential buildings, including overnight natural ventilation, short-term natural ventilation, and short-term mechanical ventilation.

By the end of 2020 all newly constructed buildings have to be nearly zero energy buildings (nZEB). In school and office buildings the ventilation system has a large contribution to the total energy use. A smart control strategy that adjusts the operation of the ventilation to the actual demand can significantly reduce this energy use. Consequently, control systems are becoming an important part of the ventilation system in these nZEB buildings.

Mechanical ventilation is vital in modern homes to insure adequate indoor air quality. However, builders, homeowners and policy makers may perceive best practice as a risk, especially if invoked during peak outdoor thermal conditions which may compromise comfort and energy use. In North America, ASHRAE Standard 62.2- 2016 defines best practice, yet ventilation code specifications vary internationally.

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.

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”.

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. 

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.

Surface condensation risk is a fact that has to be dealt with when buildings are airtight. Airtight buildings with lower ventilation rates are the result of applying energy saving policies and criteria. Surface condensation risk depends greatly on the ventilation rates, as well as on another factors such as generation of water vapour, climate, envelope components and U value, etc.

The extremes of arctic climate pose severe challenges on housing ventilation systems, energy consumption and demand for space heating for northern remote community residential buildings. As a part of the overall effort to reduce space heating requirements, dwellings are built air tight to reduce heat losses. However, airtight homes require energy efficient and effective ventilation systems to maintain acceptable indoor air quality and comfort, and to protect the building envelope from moisture damage.