design

Embedding robust yet accessible frameworks to evaluate ventilative cooling potential during the early/concept design stages for building practitioners can help in reducing the performance gap as well as avoiding vulnerability “lock-in” from design decisions that are based on poor or inadequate information. The challenge is to develop performance based evaluation methods that recognise the tacit approach to design in practice. Often design is iterative, non-linear and multi-agent.

This paper touches on historic indicators of good hospital design such as sun, daylight and natural ventilation. Evidence is provided that recent trends in hospital design that lean towards more highly serviced buildings with fixed windows lead to higher levels of Sick Building Syndrome, nosocomial infections and SARS CoV-2 related infections and deaths than in naturally ventilated buildings with opening windows.

In future building regulations 2020, building performance is going to be extended to global performance, including indoor air quality (IAQ). In the energy performance (EP) field, successive regulations pushed for a "performance-based" approach, based on an energy consumption requirement at the design stage. Nevertheless, ventilation regulations throughout the world are still mostly based on prescriptive approaches, setting airflows requirements. A performance-based approach for ventilation would insure that ventilation is designed to avoid risks for occupant’s health. 

In the field of energy performance, successive regulations pushed a "performance-based" approach, based at least on an energy consumption requirement at the design stage for heating and/or cooling systems (Spekkink 2005). Nevertheless, in the field of building ventilation, regulations throughout the world are mainly still based on “prescriptive” approaches, using airflows or air change rates requirements.  

The aim of this paper is to develop a new concept of sketch tools for the very steps of the design process. The originality lies in the use of optimization to define a global design of the building, the energy system and the control strategy. Therefore, an adapted model of the building has been realized, not directly using fine dynamic models (like those that can be found in tools TRNSYS, DOE2.2 and EnergyPlus...), but more coarse equations adapted to the sketch design phase. Those models are based on static and macroscopic equations investigating energetic and financial balances.

Calculating contaminant concentrations in or the required ventilation for a space has been a difficult and confusing part in the application of the IAQ Procedure of ANSI/ASHRAE Standard 62.1-2004; Ventilation for Acceptable Indoor Air Quality. Appendix D of ASRAE Standard 62 presents one method for performing these calculations, but it is limited to the steady-state analysis of a single zone. More recently, two software tools have been developed by the United States National Institute of Standards and Technology (NIST) to facilitate these calculations and to include transient effects.

Soil gas pollutants (Radon, VOCs, etc...) entering buildings are known to pose serious health risks to building’s occupants, and various systems have been developed to lower this risk. Soil Depressurization Systems (SDS) are among the most efficient mitigation systems protecting buildings against soil pollutants. Two kinds of SDS are currently used: active and passive systems. Active systems are mainly use fans, which enables the mechanical sub-slab’s air extraction. Passive systems use natural thermal forces and wind effect to extract air from the sub-slab.

A methodology is presented for determining the air flow rate through a stack-ventilated single-spacedenclosure bearing a roof-mounted ventilation tower. We develop a "system discharge coefficient" which takes into account the pressure losses that occur at the intake opening of the enclosure, inside the tower and at the outlet opening. The system discharge coefficient is interpreted as a reduction in the area of the path that the air flow takes. Based on this reduced area the air flow rate is then determined.

The aim of this paper is to discuss the impact of the relation between varying indoor and outdoor conditions on the ventilation loads of buildings and to provide HVAC designers with the respective information needed for the optimum dimensioning of the system. The total load generated by one litre per second of fresh air brought from the outside environment to the indoor space conditions, called -ventilation load index-, is calculated for the cities of Athens and Thessaloniki, Greece. The same principles can be applied to other locations.

Ventilation towers are often incorporated into the design of naturally-ventilated buildings. These towers increase the physical height of the building and thereby potentially enhance the buoyancy-induced air velocity. However, acoustic baffles, insect meshes, etc., placed within the towers result in pressure losses that effectively reduce the area of the flow path, thereby restricting the rate of airflow.