Final Report: Design of Sustainable Relief Housing in Africa: an Implementation of the "Cradle to Cradle" Model in Earthbag Construction

EPA Grant Number: SU832506
Title: Design of Sustainable Relief Housing in Africa: an Implementation of the "Cradle to Cradle" Model in Earthbag Construction
Investigators: Cao, Huantian , Drab, Theodore , Pearson, Jason C. , Woods, Brooke
Institution: Oklahoma State University , Green Blue Institute
EPA Project Officer: Nolt-Helms, Cynthia
Phase: I
Project Period: September 30, 2005 through May 30, 2006
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2005) RFA Text |  Recipients Lists
Research Category: P3 Challenge Area - Built Environment , Pollution Prevention/Sustainable Development , P3 Awards , Sustainability

Objective:

The urbanization in Africa results in urban poverty and homelessness. In this project, we designed a sustainable relief housing prototype that aids in sheltering homeless citizens until they are able to return to their traditional ways of life. To avoid repeating developed nations’ errors in urban development, and to consider current environmental, economic, and social issues in Africa, our design must go beyond traditional construction materials and methods to benefit people, prosperity and the planet in a sustainable way.

The purpose of this project is to implement the “cradle to cradle” design protocol in earthbag construction to design sustainable housing that is both comfortable and eco- effective for the African people.  The expected use of the designed sustainable housing is relief housing for urban homelessness.  The implementation of this project has three phases: research, design and development, and evaluation.  Ethiopia was selected as the African nation in which we will develop the earthbag relief housing.  Sustainability issues in Ethiopia were investigated. The relief housing design and development considers the geography, climate, and culture in Ethiopia. We evaluated the durability of plaster covered earthbags under sunlight to ensure the expected user period.

Summary/Accomplishments (Outputs/Outcomes):

Table 1 summarizes the geographic, climate zones and population distribution in Ethiopia.

Table 1. Geographic and climate zones of Ethiopia

Geographic zone

Climate zone

Elevation
(m)

Temp
(°C)

Humidity

Precipitation
(mm/year)

Note

 

High land

Dega (cool)

>2,400

0-16

Low

1,270-1,280

45% of the nation’s land and home to over
3/4 of the nation’s population

Woina Dega (temperate)

1,500-2,400

16-30

Low

510-1,530

Low land

Kolla (hot)

<1,500

30-50

High

<510

Sandy soil lacks nutrients

Ethiopia is home to a wide variety of cultural groups. The Oromo culture is most dominant throughout Ethiopia, accounting for approximately 40 percent of the country’s population, while the Amhara and Tigre combine for approximately 30 percent. Similarities as well as differences between cultural groups are common. Notable cultural practices include cooking, namely the coffee ceremony, dancing, story telling, the manufacturing of goods such as blankets and baskets for market, home design and layout, and family structure.

All of the three tenets of “cradle to cradle” model, i.e., waste=food, use current solar income, and celebrate diversity, are implemented in earthbag housing design to build a sustainable house that can benefit Ethiopian people, prosperity and the planet.

  • Construction materials (waste=food) All materials are biological nutrients that will return to the earth without depositing harmful additives or toxins.  Non-toxic, hydrocarbon free burlap sacks measuring 17” by 30” are filled with local soils from each of Ethiopia’s three climate zones.  Local gravels are also used. Soil stabilizers are not necessary due to containment by the burlap bags. Thorned acacias plants are laid between bags as mortar, replacing the commonly used barbed wire.  This substitution enhances the sustainability of the design by eliminating a non-biological nutrient. Fidobe plaster, made from dirt, paper, and water, serves as the exterior and interior finish, and enhances the sustainability of the design by eliminating another non-biological nutrient, cement.  Paper used in fidobe plaster will be recycled from Ethiopian waste paper.  If necessary, soil from local termite mounds may be added to the mixture, serving as a stabilizer.  Finally, natural paints are used, as well as a natural adobe flooring made from locally available materials and sealed with naturally occurring linseed oil.
  • Energy use (use current solar income) Heating and cooling techniques vary for each of the three climate zones, and include varying combinations of the following techniques.  Earthen walls 15” thick serve as thermal masses in order to negate thermal fluctuation.  Surface color is dark in cooler areas in order to absorb heat, and light in warmer areas in order to reflect heat.  Space surrounding the structure is allotted for the planting of dense foliage in cooler areas, and lighter foliage in warmer areas.  Relief housing is recessed into the ground between two feet and four feet in order to negate thermal fluctuation.  Finally, windscoops, windows, and overhangs are incorporated into to the design as necessary in order to facilitate air flow and block sunlight respectively.
  • Housing and interior design (celebrate diversity) This sustainable relief housing mimics the traditional Ethiopian tukul through the use of a domed structure. Considering geography, climate and the culture of Ethiopia, the relief housing has a common area, cultural area, family area, and bedrooms. Design decisions for each of the areas were made using a process known as evidence based design in which design decisions are supported by scholarly research or existing preceden. The relief housing was designed as a kit of parts, which may be assembled in various combinations as necessary based upon climatic conditions.  The kit includes the following components: (1) large dome measuring 20 feet in diameter, (2) medium dome measuring 17 feet in diameter, (3) small dome measuring 14 feet in diameter, (4) overhang system, (5) windscoop, (6) openings, and (7) planting area. One example of a combination of these parts may be seen in Figures 1 and 2. Table 2 summarizes the kit components and their uses followed by complementary discussion of the housing design. Traditional arrangement of extended family structures facing an open area is maintained.  Housing design is based on African fractals in keeping with tradition, and the finished structures remain unpainted in order to accommodate the Ethiopian practice of building painting. Each structure accommodates up to twelve occupants with a minimum of 10m2 floor area allotted per person, in keeping with Ethiopian living practices. Native furnishings are incorporated into the design.

Figure 1: Kit Component Combination Example – Kolla Climate Zone Elevation

Figure 2: Kit Component Combination Example – Kolla Climate Zone Plan

Fidobe plaster is used as the housing exterior to improve durability under conditions of intensive sunlight exposure. The material evaluation demonstrated that natural plaster covered burlap earthbags are durable for at least 1 year of sunlight exposure in Ethiopia. Considering Ethiopian culture where housing exteriors are annually re-plastered, we can expect the housing can be used for at least 10 years.

Table 2. Kit Component Summary

#

Component

Description

Purpose

Climate Zone

1

Large  Dome

Earthbag dome, 20’
diameter.

Accommodations for 12: Extended
family activities.

All

2

Medium Dome

Earthbag dome, 17’
diameter.

Accommodations for 6-8: Family
activities.

All

3

Small Dome

Earthbag dome, 14’
diameter.

Accommodations for 2: sleeping.

All

4

Overhang

Horizontal projection from dome; locally available thatch material.

Moisture protection

Woina Dega

Shading of structure

Kolla

5

Windscoop

Vertical, tunnel-like projection from dome, earthbag construction.

Ventilation

Woina Dega

6

Openings

Doors & windows.

Solar Heating

Dega

Ventilation

Kolla

7

Planting Area

Box like surround, earthbag construction.

Insulation

Dega

Evaporative Cooling

Woina Dega, Kolla

Food Source

All

 

Conclusions:

This project benefits Ethiopian people in people, prosperity, and the planet perspectives. With locally available materials, inexpensive construction, maintenance, and use, this project provides affordable shelter for Ethiopian people. All construction and interior design materials are naturally occurring, and will return to nature after use, ensuring the most effective using of material resources, no synthetic material and toxin deposition, and the best indoor air quality for human health. Using earthbags rather than wood for the structure, this housing design addresses one cause of deforestation and the resulting desertification in Ethiopia. Implementing “cradle to cradle” design model in earthbag construction achieves all three aspects of sustainable development: environmental, economic, and social welfare.

This project addresses the sustainability issues related to relief housing in a developing country, Ethiopia. However, the design and findings in this project can also be applied in developed world. Using locally available materials and inexpensive construction, the “cradle to cradle” earthbag technique can be used to build relief housing for citizens in developed countries such as victims of natural disasters including hurricanes, tornados, and earthquakes.

Journal Articles:

No journal articles submitted with this report: View all 4 publications for this project

Supplemental Keywords:

green building, waste reduction, life-cycle analysis, land, water, RFA, Scientific Discipline, Sustainable Industry/Business, POLLUTION PREVENTION, Sustainable Environment, Energy, Technology for Sustainable Environment, Environmental Engineering, Urban and Regional Planning, energy conservation, sustainable housing, earthbag construction, sustainable development, environmental conscious construction, environmental sustainability, alternative materials, energy efficiency, solar energy, construction material, architectual design, environmentally conscious design

Progress and Final Reports:

Original Abstract