heat recovery

Improved insulation of domestic buildings has resulted in ventilation heat loss forming a large part of the total heat loss. Estimates show that energy consumption in the Federal Republic of Germany could be reduced by ventilating design methods eg by economical ventilating systems suitably adapted to theheating installations. A number of technical facilities exist for the utilisation of this potential, which at the same time maintain the necessary requirements for indoor climate.

Describes the conditions of the "Heat Recovery from Exhaust Air" group of projects of the Swedish Council for Building Research. 

In a modern residence with reduced air infiltration, a problem may arise if the fresh air requirement is left to natural leakage. The article discusses this problem, and describes techniques for measuring air leakage and typical results. The contaminants which define the need for ventilation are described and the case for controlled ventilation systems (and possibly heat recovery devices) is made. Areas for further research are recommended.

Reports on single family dwellings fitted with energy-saving ventilation unit. Quotes energy savings of 10,000 Kwh/annum. Points out that adequate indoor climate can be maintained through tight houses, mechanical ventilation and heat recovery as opposed to airing rooms by opening windows.

Considers the options which could be described as heat recovery and which are open to building services designers and operators. Treats fundementals for heat recovery, inadvertent heat recovery, deliberate heat recovery, air recirculation, passive heat exchangers, active heat exchangers, heat pump systems, heat recovery systems, incremental systems, heat distribution in central plant heat recovery systems, controls, heat recovery in air conditioning systems, bivalent heating, the actual application process of heat recovery.

Makes general suggestions for future buildings and their ventilation methods with the aim of creating improvements to avoid the faulty design of the 1960's with their high energy consumption. Considers the characteristics of natural ventilation and mechanical ventilation with respect to ventilation heat loss. Recommends the use of `ventilation on demand' for bathrooms, w.c.'s and kitchens using individual extract ventilation units for each room.

Considers the reasons for advocating mechanical domestic ventilation. Discusses which factors provide for an optimum climate in rooms. Treats room temperature, air movement in the occupied zone, air purity and humidity, odours, noise. Illustrates how mechanical ventilation should be arranged to provide correct indoor ventilation and the different ventilation principles involved: gravity ventilation, fan-assisted exhaust ventilation and supply and extract ventilation. Illustrates typical applications of these systems to single family houses.

The performance of an HVAC system's air-to-air energy recovery exchanger is defined primarily by the exchanger's effectiveness and pressure drop. The effectiveness is dependent on several parameters such as the supply and exhaust mass flow rates and the energy transfer characteristics of the device. Because of this combination, performance data must be established for each individual type of device.

Notes that as houses become tighter, adventitious ventilation decreases. Discusses attitudes to varying degrees of tightness. Explains introduction of the supply exhaust system which comprises air supply, air exhaust and heat recovery. Notes requirements for economic use of the system and relates installation costs to potential savings. Tabulates systems currently available in Sweden(December 1980)noting maximum air flow, position of heat exchanger and other factors.