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Numerical Evaluation of Earth to Air Heat Exchangers and Heat Recovery Ventilation Systems

Balanced ventilation systems with heat recovery and earth to air heat exchangers are interestingtechniques, which can reduce heating and cooling demand of buildings, and improve internal thermal comfort. A numerical study is carried out to evaluate the impact of these two systems on the energy consumption and thermal comfort of a single family house. The impact on the CO2 emission is also given.

Ventilation - The challenges and achievements

Major ventilation developments covering systems, measurements and design methods have taken place over the last 25 years. Our understanding about the impact of ventilation on the indoor environment and energy use has also evolved. This paper outlines these developments. Many future challenges are considered including minimum ventilation rates, energy efficient cooling, cost effective heat recovery and the development of calculation techniques.

Solutions for MVHR in existing dwellings

For retrofitting of existing dwellings MVHR is seldom applied, despite the potential in energy saving and improving thermal comfort and indoor air quality. Major barriers and limitations for application are lack of space, especially for the supply ducts and the MVHR units as well as the complexity of execution. Also initial costs are an important barrier. Limiting supply ducts could be beneficial for application in single family dwellings. In a study some configurations with simplified air supply with MVHR in single family dwellings have been investigated.

Heat and mass transfer analysis of cross-flow heat exchanger for energy recovery from exhaust air

Problems of heat and mass transfer optimization in the plate cross-flow heat exchangers, usedin air conditioning systems for energy recovery from exhaust air, are discussed. The mainpeculiarity of the investigated unit is the possibility of realization of heat transfer withinexhaust air canals in the dry heat exchange conditions or in the conditions of coupled heatand mass transfer with occurrence of vapour condensation on the whole or on a part of theheat exchange surface of the matrix in the form of dew or frost.

Wheel selection for heat and energy recovery in simple HVAC ventilation design problems

This paper shows how air-to-air heat and energy system design problems can be formulated for a simple HVAC configuration and solved for the least life-cycle cost system while still retaining a small payback period. Mathematical expressions and design tables are presented to facilitate the design process. The design process is illustrated for the city of Chicago where both large heating and cooling loads occur in HVAC applications. The example design problem presented shows that

Energy Savings potential of energy recovery ventilation in an Animal Housing Facility

This paper summarizes efforts to identify economically viable strategies to reduce HVAC-related energy use while improving the indoor air quality for a public zoo facility that houses primates and large cats. The primary focus of energy conservation strategies for the facility centered on use of airto-air energy recovery devices. Computer simulations, validated with experimental data from the facility, were used to estimate energy savings for alternative energy conservation strategies.

Heat recovery in building envelopes

Infiltration has traditionally been assumed to contribute to the energy load of a building by an amount equal to the product of the infiltration flow rate and the enthalpy difference between inside and outside. Some studies have indicated that application of such a simple formula may produce an unreasonably high contribution because of heat recovery within the building envelope. The major objective of this study was to provide an improved prediction of the energy load due to infiltration by introducing a correction factor that multiplies the expression for the conventional load.

Humidity control in offices in the Belgian climate

In the survey study ‘Kantoor 2000’ the HVAC-system of several large office buildings in Flanders was monitored. Some of these buildings use air humidity control, most of them not. This triggered the question : why? In this paper the humidity control strat

Accurate performance testing of residential heat recovery units

The Norwegian Building Research Institute (NBI) has completed a study of the performance of balanced residential ventilation systems with heat recovery (HRVs) in Norway. The study involved both a national questionnaire survey and thorough laboratory tests of 10 HRVs on the market. The overall conclusion is that balanced ventilation with heat recovery provides very good air quality, and has a payback time of 4~6 years for the most profitable systems despite Norways cheap hydropower (0.09 /kWh in 2002).

Total energy performance of the air conditioning system using outdoor air cooling potential

From the view point of designing the energy efficient air conditioning system with maximized ventilation, the possibility of an all fresh air system was discussed using the simulation results of a model building in Tokyo. The algorithm of single duct cooling system for simulating the cooling coil of air handling unit based on the heat balance model of whole system components is also described as a base for the simulation of cooling effect of ventilation fresh air.

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