Smoke Hoods

Overview

According to the World Health Organization (WHO) as many as 1.9 million people die each year as a result of indoor air pollution (IAP).  The overwhelming cause of this pollution is inefficient und poorly ventilated cooking and heating with solid biomass. Smoke hoods are an excellent alternative to alleviate the dangers related to smoke from open fires as they draw the smoke out of the house. This makes the indoor air much cleaner and healthier.

What is a Smoke Hood

Smoke hoods consist of a main stove body, from which a flue takes the polluting gases out of a house through the roof. In many ways they can be matched to the traditional fireplaces or improved cookstoves (ICS) found in households all over the world for cooking, boiling water, lighting or heating. In hot regions, a hood made of insulating material can take away much of the heat out of the kitchen. In cold regions, the hood can be built to allow the family to benefit from the radiant heat of the fire. In both cases the hood can allow for smoking of meats or other ritual or traditional uses of an open fire.

Impacts

The installation of a smoke hoods can be extremely effective in  improving the air quality in houses. This applies especially, when traditional biomass burning stoves are being used without a chimney. In addition, some efficient stoves may not be clean and therefore employing a smoke hood allows for health benefits coupled with lower operating costs. Moreover, in some cultures, an open fire plays a special social role as a place around which the  family gathers, traditional meals are cooked or other important rituals. As a result the introduction of improved cookstoves is difficult and a smoke hood serves as the best alternative for improving indoor air quality.

Concurrently, although the health impact can be significant, the environmental impact is not necessarily reduced because - methane and other greenhouse gas (GHG) emissions are not as dramatically reduced with a smoke hood as with an efficient cookstove. However smoke hoods can also be integrated with lower-cost, locally made, more efficient cook stoves that, combined with a well-designed smoke hoods can reduce IAP up to 80%.

Target Group

Families which are currently cooking on open fires with biomass or charcoal are the target group for smoke hoods. Specifically those families that for cultural or other reasons do not wish t or are unable to adopt an improved cookstove. This is especially the case in regions where an open fire is used for heating or smoking purposes.  And, in circumstances where low-cost efficient (but not clean) cookstoves are available, a smokehood can be combined as an integrated system to both improve efficiency and reduce indoor air pollution (IAP) at optimal cost and offering the users the greatest comfort, flexibility and overall cost-benefit.

There are different traditional and practical reasons, why people are cooking on open fires:

• People are used to cook on open fires
• People are very poor and wood and agriculture residues are for free
• Other or cleaner technologies and fuels are not available or not affordable
• It is cold and the fire is also used for space heating
• Traditionally the family is sitting around the fire
• The smoke kills vermin in the thatched roof
• Users wish to smoke meats or fish

The smoke hood technology may not be a good solution for every culture or region. The potential for an adequate cost / benefit, user acceptance and subsequent impact of introducing smoke hoods in a given setting are affected by several criteria.

Those that lead to a positive scenario include, but are not limited to the following:

• No alternative options that might have a greater combination of benefits than smoke hood
• Generally simple pot cooking is practiced
• Users reject other improvements due to cultural or other reasons
• Internal dimensions that allow the cook to use familiar cooking practices
• Biomass and charcoal are used by the majority
• Materials and production skills within the community exist to produce the hoods locally
• Certain level of manufacturing possibilities is available like bending
• Access to necessary raw materials like sheet or recycled metals
• Good transport networks that allow hoods to be entirely or partially manufactured elsewhere
• Access to small-scale credit funds

"Healthy Hoods" Project

Although basic designs for smokehoods had been tested in the past, their effectiveness usually remained at around 60% smoke reduction and therefore below WHO standards.  However,  Bosch and Siemens Home Appliances Group (BSH) together with the Universität der Bundeswehr München and Practical Action with support from the Deutsche Entwicklungs Gesellschaft (DEG) have recently developed and improved design that removes over 80% of the smoke and meets WHO standards.

Further Information

• Project Homepage: Healthy Smoke Hoods / Practical Action
• Smoke Hood Designer (by Practical Action and BSH)
• Chimney Stoves and Smoke Hoods - technical brief by Practical Action)
• Homepage Bosch Siemens Homeapliances Group
• See also Heating - Indoor Air Temperature