ventilation

Worldwide the food system is responsible for 33% of greenhouse gas emissions. It is estimated that by 2050, the total food production should be 70% more than current food production levels. In the UK, food chain is responsible for around 18% of final energy use and 20% of GHG emissions. Estimates indicate that energy savings of the order of 50% are achievable in food chains by appropriate technology changes in food production, processing, packaging, transportation, and consumption.

The experiments are carried out in a climate chamber located at the Department of Civil Engineering Aalborg University. The objective of the experiments is to evaluate the performance of the system combining diffuse ceiling ventilation and thermally activated building construction (TABS) in terms of thermal comfort and energy performance. 20 cases with different boundary conditions are conducted varying on climate condition heat load. TABS water temperature and flow rate with or without diffuse ceiling.

Regional climate change in cities is the most documented phenomenon of climate change . Higher urban temperatures are  documented experimentally for more than 450 major cities in the world. Numerous investigations demonstrate that the mean magnitude of the temperature increase may exceed 4-6 C, while at the peak it may exceed  10 C. The serious increase of the frequency and the strength of heat waves creates strong synergies between the global and regional climate change and intensify the magnitude of the overheating 

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.  

As a consequence of the sustainable politics demanding regulations that allow the use of more efficient ventilation systems, the IAQ Spanish regulations were modified and enforced in 2017. The new regulations became performance-based in order to accommodate the use of systems which are capable of adapting required ventilation rates to real needs. The new requirement is based on both CO2 concentration and a minimum ventilation rate. 

The new IAQ requirement is able to keep acceptable IAQ values and to reduce energy demand in relation to the previous IAQ requirement. 

Humidity-based DCV systems have been widely used in France for 35 years and are considered as a reference system, including for low-energy residential buildings. Indeed, most of the new residential buildings, which must be low-energy buildings to comply with the RT 2012 energy performance regulation, are equipped with such systems. Feedbacks from two long-term studies show the durability of the humidity sensitive components and show the robustness of this system to bad maintenance or use by occupants.

The modelling of air flows to investigate indoor air quality and energy issues has been a topic at the AIVC for all of its 40 years. Models have been developed that range in complexity from single-zone algebraic expressions that can be calculated by hand to complex multi-zone approaches that integrate contaminant transport and other functions.