heat recovery

In the frame of the European project called Bricker, a new prototype of single room ventilation with heat recovery has been developed. This new unit is supposed to be installed in class rooms of an educational institution. This paper deals with the development of the first prototype of this unit. An empirical model of such device is also proposed in order to be coupled with a building model. This aims at determining the seasonal performance of the device and thus the potential energy saving (compared to other technologies) resulting from its use.

A heat recovery ventilator (HRV) is used to create a balanced ventilation system in residential buildings and as an energy-saving measure. HRVs bring in outside air which is tempered with outgoing stale air, with only the small energy penalty of the blower power to overcome the pressure drop in the HRV. HRVs have been used in cold climates and have often performed poorly due to frosting failure.

Mr.Platts briefly reviews current Canadian housing and the potential for controlled ventilation with exhaust air heat recovery. Discusses cost effectiveness of exhaust air heat recovery and suggests that payback periods are generally too long and hence uneconomic. Mr.Bonnyman discusses the market for domestic heat recovery units. Briefly reviews the types of heat recovery equipment. Gives product information for units available in Canada.

The article describes the results of an experimental campaign carried out at ITC-CNR in outdoor test cells to evaluate the energy performance and the related comfort level achieved through a coupled system made up of a dynamic window and a heat recovery unit.

Central ventilation systems with heat recovery have shown their limits especially within the context of building energy retrofit. The difficulties to install these systems in existing buildings, to find available space for devices, air ducts, silencers and fire dampers and to independently control the air flow in each room according to the real ventilation needs have led to an increasing market for decentralized ventilation devices.

An office building of the Fraunhofer Institute for Solar Energy systems (Fraunhofer ISE) in Freiburg was retrofitted in 2012 with an innovative concept based on technology integration in the façade. Prefabricated window modules integrating air inlets and outlets, façade integrated air ducts and a heat and moisture recovery ventilation device were implemented. A long term monitoring was set up including energy, temperature, CO2 and humidity measurements.

We have developed a simple model to estimate ductwork leakage and heat conduction losses in steady-state conditions for a balanced ventilation system. Implemented in a spreadsheet, it allows us to calculate their impact on heat recovery efficiency consistently with EN 15241 without the need for a dynamic simulation tool. One case study shows that the global heat recovery of a balanced ventilation system with a nominal heat recovery of 80% can be reduced to less than 50% if the ductwork leakage and thermal resistance are poor.

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The present paper focuses on a new single room ventilation with heat recovery. Double flow ventilation is achieved through the integration of the unit into windows ledges. The developed device is particularly suitable compared to traditional centralized heat recovery ventilation units for retrofitted houses due to the absence of air extracting and air pulsing ducts through the house. 

Heat recovery ventilation became an unavoidable element of a passive or nearly zero energy building in Northern and Central Europe countries. Airtightness standards became very tight so that the building is compatible with this ventilation system. As frosting of heat recovery unit consumes a lot of electrical energy, a buried pipe system to smooth air temperature variations became also a necessary system in order to avoid defrosting.

Worldwide the food system is responsible for 33% of GHG emissions. It is estimated that by 2050, 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.