The Design of theHabitat Research &Development Centre

(HRDC)

Published by:

HRDCWindhoek

September 2006

Credits Plans: N. Maritz Photos: M.A. Wienecke

Clay House Project, Otjiwarongo (Otji-toilet) Internet: http://www.yazd.com/, http://www.allempires.com/

Text: N. Maritz M.A. Wienecke

Vision

To be the center of excellence in housing researchand development by applying new methods and ideasof science and technology for the sustainabledevelopment of the Namibian housing sector.

Mission

To promote the use of local, indigenous buildingmaterials and designs, to engage multi-disciplinaryteams in basic research, the adaptation of existingknowledge and applied research to achieve a holisticapproach to problem solving in the field of housingand its related issues.

ObjectivesThe Habitat Research and Development Centreshall be the focal point for research anddevelopment of the Namibian housing sectoraimed at promoting sustainable human settlements.To achieve these goals, the HRDC aims at:

promoting the production and usage of localbuilding materials through appropriatetechnologies and design;

advocate, promote and facilitate ecologicalsanitation, water conservation, renewableenergy and biodiversity;

support communities, local and regionalauthorities in capacity building related tohousing issues;

disseminating information to stakeholders; and contributing to policy formulation on housing,

environment and resources management.

CONTENTS

Background 1Activities of the HRDC 1Layout plan and phases 2Facilities offered by the HRDC 2Design 3 Orientation 3 Ventilation 3Energy 3 Energy efficiency 3 Lighting 4 Cooking 4 Cooling 5Water and sanitation 6 Sanitation systems 6 Features of dry sanitation 6 How dry sanitation works 7 Water supply and drainage 9 Rainwater collection 9Alternative construction materials 9 Compresssed soil-cement blocks 9 Recycled cement bricks 10 Sun-dried clay blocks (Adobe) 10 Burned clay bricks 11 Rammed earth 11 Tyres 12 Rubble gabions 12 Local stone 12 Sample walls 13 Screens 13Roof support strcutures 14Flooring 14 Internal flooring 14 Exterior paving 15 Ceilings and insulation 15 Finishes 15Networking 16

BackgroundThe Ministry of Regional and Local Government, Housing and RuralDevelopment (MRLGHRD) had, as part of NDP II, made provision forthe establishment of a national research institution. The HRDC willbe active in various fields of housing and human settlementdevelopment. The MRLGHRD provides seed funding to construct andoperate the HRDC. To achieve the objectives, cooperation with thevarious government ministries, University of Namibia, the Polytechnicof Namibia, NGOs and CBOs, professional organisations, local andregional authorities, is supported.

Tasks of the HRDC Providing a central information resource centre focusing on

housing and related matters; Promoting housing that is appropriate and affordable to Namibia; Liaising between different interest groups, pooling resources,

and creating a housing network; Researching local housing conditions, training needs, sanitation,

energy, building materials and construction techniques; Promoting alternative housing and urban settlement designs; Facilitating the development of management and other skills in

SMEs in the building sector including skills in alternativeconstruction methods and techniques;

Educating the public at large on housing issues; and Providing advisory, consultancy and project management services.

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Layout plan and future phases

Facilities offered by the HRDCAt present the following facilities are available:

Library and resource centre; On-site exhibition space for innovative building methods; Display areas for products and materials; Office facilities for national and international housing researchers, consultants and specialists; a multi-purpose hall for 35 - 40 delegates with kitchen; and an exhibition area for show houses.

The next phases include the construction of:

Two lecture halls for 150 - 160 delegates;and Four workshops for training programmes.

Future conference halls (2007)

Future workshops (2007)

Show house area

Existing offices

Library and exhibition hall

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Design aspects

OrientationThe public wing (kitchen, library, and exhibition hall) are elongated alongthe east-west axis. The building is north-facing, whereas the office wing isangled 25 east of north.

VentilationCross-ventilation was provided by placing openings directly across eachother. Ceilings were fixed above the roof structure to allow a higher internalvolume, so that the rising warm air could accumulate above head height.Clerestory windows allow the escape of rising warm air, which is supportedby the upward slope of the ceilings.

EnergyEnergy efficiencyStrong emphasis was placed on energy efficiency, as the generativepotential of the Centre is small compared to the potential savings inconsumption.

Around 60% of the energy used at the HRDC is coming from the sun. Twosolar roofs have been installed with 44 panels of a maximum of 120 Wpeak. Excess energy generated by the HRDC can be fed into themunicipal grid and can then be used by Windhoeks inhabitants.

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LightingWindow openings maximise daylighting. The side windows andcentral clerestory windowdistribute daylight equally. Lights only need to be switched on at night oron overcast days. All light fittings are low-energy fittings (fluorescent orcompact fluorescent).

CookingSeveral cooking methods are available for demonstartion: solar boxcookers (chicken size and goat size) and a parabolic cooker. The boxcookers are manufactured in Ongwediva and can be ordered from theHRDC.

In addition, various wood efficient stoves are on display, such as the Vesto,TsoTso and the rocket stove. They consume less than half the wood of anopen fire. The Vesto can utilise the Bushblocks very efficiently, which areproduced from invader bushes.

Cooling A passive downdraft evaporative cooling (PDEC) system was built for thepublic area. This is based on designs developed in Persia many centuriesago. Badgirs were invented in Yazd to cool the people's residences. Windis caught in the towers, where water containers help to cool and moistenthe air during the summer time.

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Examples of wind towers in Sirjan and Yazd, Iran (from the Internet).

At the HRDC, a water pond has been incooperated in the design of thetowers to cool the air before entering the various rooms.

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Water and sanitationSeveral strategies were employed to save water at the HRDC, in particularwith regard to sanitation.

Sanitation systemsAll toilets in operation at the HRDC are dry sanitation systems. This refersto systems that do not require any water for the disposal of waste. Thesetechnologies do not only save water, but also do not contaminate theenvironment and groundwater resources.

Dry sanitation is an on-site system, stand alone system, which does notrequire a connection to an existing sewer network.

Features of dry sanitation include:

No plumbing required No drains No pipes Waterfree Odourless Chemical free Relatively easy to build and install

All toilets at HRDC are dry or composting units. They were installed fordemonstration and testing purposes. The types of toilets used in the publicablutions are the Enviroloo, a local builders Cool-drawer design, the Jo-Jo toilet and one specially developed for the project - the Mark I.

Toilets at the HRDC1. Mark I: The HRDC toilet Mark I is testedin the public ablution building and relies onan in-situ brick built composting tank withtwo wire baskets [a] lined with containerbags made from polyethylene feedbags andventilated by an exterior chimney withrotating self-propelled wind turbine extractor.The potential advantages are: constructionby local semi-skilled people using locallyavailable materials, upkeep and servicing bythe users, lower costs and scope forimprovement.

2. Cool drawer toilet: This system uses a sliding device, containing aplastic bag underneath the toilet. Once the bag is full, it can be easilyremoved to a composting pit or heap. A new bag is placed in the deviceand moved underneath the toilet.

3. Double chamber toilet: The system consists of two chambersunderneath the toilet. Only one chamber is in use, whereas the other onecontains waste, which is in the process of being composted. Once achamber is full, the toilet is moved over to the empty chamber and the holeis closed.

4. Manufactured units: Two manufactured products have been included inthe design. They are the Enviroloo and the Jo-Jo toilet.

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Enviroloos at the HRDC

Section through the Enviroloo The Jo-Jo toilet (Image: JoJo)

How dry sanitation worksNamibia is known to be the driest country south of the Sahara. Thereforewater is a scarce resource in urban as well as rural areas. Nevertheless,conventional waterborne sewer systems are found all over Namibia. Theyare promoting a flush and forget technology. Waterborne systems weredeveloped in countries with a high rainfall and did not have to be concernedwith water availability.

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5. The Otji-toilet: The Otji-toilet design was inspired by the dry sanitationprinciples. Due to increasing cost of purchasing systems from SouthAfrica, a local version was developed. A two cubic meter tank underneaththe toilet is constructed to hold two bins and composting bags. Using adrill, holes are drilled into the bin to enable liquids to escape. Together witha perforated plastic bag, the collectors are placed underneath the toilet.Liquid flows through a perforated concrete panel into a second space fromwhere it filters into the ground.

The Otji toilet(Images aboveand left by CHP)

An alternative to the disadvantages of conventional sewer systems is drysanitation. It is part of the ecosan (ecological sanitation) approach, whichpromotes the recycling of resources, lowers water consumption,substitiution of chemical fertilizers, and is much more cost efficient andaffordable. Potable water is used to transport the apparent waste tocentralised treatment plants. This is unsuitable in areas with waterscarcity, as this leads to high water consumption. Especially urban areasare wasting water as they are powerful enough to have water transportedover long distances to be consumed by its population.

Waterborne systems are very expensive to build and to maintain. The driedfaeces obtained from an alternative system, has soil improvement qualitiesand increases water retention capabilities. It is a fertilizer, compostmaterial or source of energy, for example, when used in a biogas digester.Therefore faeces and urine can be recycled and used as nutrients.

A further development of the dry sanitation system is the urine diversiontoilet system (UDS). Urine has a very high proportion of natural nutrientsand can be directly applied to plants. Urine contains about 90% of the totalnitrogen, 55% of the total phosphorus, and a proportion of potassiumcontained in human excrement. Due to the low volume, a UDS is collectingurine separately. Dry sanitation, as well as a Urine Diversition System, canbe installed indoors. To prevent smell, building lime, wood ash or wheatbran can be used inside the toilet. Maintenance is easy, as larger systemsneed to have the dried contents removed, on average, once a year.

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groundwater recharge

irrigationwater

nutrients

agriculture

purification byrootzone treatment,stabilisation ponds,technical treatment

nutrientsorganicstrace elements

urine

faeces rainwaterinfiltration

greywater

reuse

drinking watertreatment

rainwater

organicwaste

food

servicewater

biogas,compostingplant

purification if necessary

drinkingwater

hygienisation

advantages of ecological sanitation systems

ecological sanitation

ecosanecosan closing the loop in wastewatermanagement and sanitation

Deutsche Gesellschaft frTechnische Zusammenarbeit (GTZ) GmbH

Environment and Infrastructure

International Research and Development Projectecosan ecologically and economically sustainablewastewater management and sanitation systemswww.gtz.de/ecosan

on behalf of:

fertiliser factory

drinking water

falling groundwater level

incineration

landfill

partial utilisation of sewagesludge and nutrients

agriculture

phosphorus(limited fossil resources)

potassium

nitrogen(high energy demand)

partiallytreated wastewater

sewage sludge

pollution withpharmaceuticals, hormones,organics, bacteria, nutrients

sewagetreatment plant

(only 5-10% of totalwastewater worldwide)

wastewater

drinking watertreatment

rainwater

food

shortcomings of conventional wastewater systems

Deutsche Gesellschaft frTechnische Zusammenarbeit (GTZ) GmbH

Environment and Infrastructure

International Research and Development Projectecosan ecologically and economically sustainablewastewater management and sanitation systemswww.gtz.de/ecosan

ecological sanitation

ecosanecosan closing the loop in wastewatermanagement and sanitation

Deutsche Gesellschaft frTechnische Zusammenarbeit (GTZ) GmbH

on behalf of:

Water supply and drainageThe HRDC is demonstrating and testing a wide range of water-savingoptions. All taps are fitted with water-saving aeration devices, which can befitted to existing fittings and the public ablutions with demand taps. Ashower is located in the public ablution building for use by the maintenancestaff. Grey water from sinks and hand washbasins are drained throughfilters. The kitchen sinks are connected to a greasetrap and strainer.

Rainwater collectionRoof-water is collected from the roofs and stored in stacked rainwatertanks to serve cooling systems as well as irrigate gardens. A municipaldomestic water connection serves as a back-up. The plastic water-tanksare elevated in the towers to create pressure and are shaded by timberpole screens to reduce the effect of the strong local sunlight on thematerial.

Alternative construction materialsLoad-bearing structures were mostly used, as frame-and-infill structuresrely on expensive timber or steel and thin-skin infill is unsuitable forclimatic conditions where thermal mass is desirable. Timber is also ascarce resource in Namibia with no managed plantations in the countryand deforestation becoming a problem. The variety of walling systems usedfocused on high labour content and local materials rather than fast-trackpre-made systems imported from afar.

Compressed soil-cement blocksThe Namibian invented Hydraform system uses an on-site mixer andhydraulic compressor to make cement-stabilised soil blocks. As theavailable soil did not have enough clay content to act as binder, 6 to 8 %cement was added, producing blocks of about 4 MPa. The blocks areprofiled and interlock when dry-stacked without mortar. Soil was sourcedfrom a stockpile at Otjomuise, a few kilometres away.

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Recycled cement bricksCement bricks were reclaimed by hand from building demolition rubbledumped by the Municipality next to the site. They were cleaned usingunskilled labour on a cost per unit basis and then reused during theconstruction.

Stockpile, productionand construction withsoil blocks

Sun-dried clay blocks (Adobe)Sun-dried clay blocks made by the Namibia Clay House Project have beenused to build the public ablutions. Although clay has to be brought in, it isvaluable to demonstrate the use of these 300 x 300 x 100 mm blocks thathave been used to successfully construct over 200 houses in Otjiwarongo.

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Burned clay bricksStock brick quality clay bricks are produced by two Namibian companiesin Mariental and near Kombat. These are an alternative to the cementbricks. The products create employment with labour-intensive production.Charcoal used to fire the bricks near Kombat is made from invader Acaciamellifera and Dichrostachys cinerea bushes. The structural qualities arehigh and the bricks were used for the multi-storey sections of theproject.The walls are not plastered, giving a warm textured reddish lookand demonstrating that plaster is not required in the dry Namibian climate.

Rammed earthRammed earth using the same constituents as the Hydraform was used forthe exhibition hall. Sample walls were first built on site to experiment withthe mixture. 4% cement were added to the soil. Wall sections with this 4%cement mixture were built as load bearing walls. Panels with 2% and 0%mixes alternated as infill panels. The walls were constructed with reusablesteel shutters and the compaction was done by handramming.

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TyresTyre walls for archive storerooms were built using earthship techniques,filling layers of tyres with compacted soil. Old tyres cannot be recycled inNamibia as the quantities are too small, but they can create landfillproblems. Walls are unplastered to demonstrate the system, whereas theinterior walls of the store rooms are painted white for light reflection. Tyreretaining walls for terracing were also built next to the river to stabilise theembankments.

Rubble gabionsWire basket gabions filled with concrete rubble from a demolition site wereused for a retaining-shading wall for the offices. Gabion baskets were madeon site by workers from fencing wire and chicken mesh.

Local stoneMica was obtained from a nearby filling station site for the outdoorbalustrade walls. The HRDC contractor sourced it soon after the concept of

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materials was explained and obtained several truckloads for free, as thefilling station contractor had to remove the stones.

Sample wallsSample walls for basic tests and demonstrations were built in the foyerusing sandbags, straw bales/cob, adobe bricks, river stone, glass bottles,mortar and rubble, polystyrene blocks, and the Easy BuilderTM.

ScreensVarious screening methods were utilised for solar protection and security.Poles were cut by unemployed, unskilled workers from prosopis trees, andwere soaked in used motor oil (insecticide and weatherproofer), and usedas screens for windows, gates and to shade overhangs and water tanks.The poles were fixed to steel support frames with self-tapping roof screws,and on the shaded walkways, wired to the steel frame. In this way theycan be removed at a later stage when they are replaced by solar panels.

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Roof support structuresThe pipes for the support of the roof are second grade steel. The pipes areused in various configurations to demonstrate options from traditionaltrusses to single short-span purlins directly on walls. Other materialsdemonstrated are brickwork vaults, a pin-jointed space-frame and a short-span purlin-only system made from prosopis poles. Soft wood deterioratesvery quickly in the dry heat and termites are a perennial problem. Mosttermicides still sold in the country are organo-chlorides banned under theStockholm convention. Environmentally friendly ones are now available.

Roof coveringsThe use of corrugated steel sheeting as the dominant roofing material wasbased on several reasons: the long lifespan, lower initial cost and potentialre-use make it far more efficient from an embodied energy viewpoint,compared to the other available materials utilised. They include thatch andmicro concrete tiles, because large tiled roofs need a stronger and heavierroof structure. Thatched roofs in an urban area have a high fire-risk due tofrequent lightning storms. Neither thatch nor tiles are dust-proof. All thematerials have to be transported to Windhoek from afar. For the areacovered, corrugated steel sheeting has the least weight and volume.Second hand corrugated sheeting was used on the public toilet building.

FlooringInternal flooringWax-polished concrete surface beds were used for offices where dustcontrol was important and packed clay bricks on a sand bed for the

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exhibition hall and lecture room. Both finishes have high thermal mass andabsorb body heat by radiation while being hardwearing, inexpensive andeasy to maintain.

Exterior pavingWaste mica stone was used with a clay beddinglayer for external paving, interspersed with gravelstrips to allow immediate rainwater penetration.Round boulders sourced from debris from recent floods were used forapron edges around buildings to reduce water splash. Cubes fromconcrete testing laboratories make strong surfacing for ramped roadwaysin the parking area.

Ceilings and insulationAdequate insulation was a priority due to the roofsheets thermal inefficiency. A material that couldsupport various insulation types as well as providesome insulating value itself was reed. The invasivereeds occur in seasonal riverbeds and are a floodhazard. Between the reeds and roof sheets threeinsulating materials were utilised:

Low-grade wool mixed with dried lavender leaves (to act as natural anti-moth agent) packed into second-hand feedbags. Waste polystyrene packaging (100 mm thick). Flattened cardboard boxes (60 mm thick).

FinishesSurfaces were retained in their natural state wherever possible, to showconstruction methods and the aesthetic potential.Where needed for weather and corrosionprotection, water based paints and sealants wereused to reduce pollution and for health reasons.The soil-cement blocks are coated outside with awater-based clear silicate sealant against waterpenetration. Two sealants were tested on therammed earth walls.

Interior walls are lime-washed white to increase the day-lighting effect.White roadmarking paint was used inside on the tyre walls for the samereason.

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Habitat Research & Development CentreP.O. Box 63036

Wanaheda, Windhoek

Claudius Kandovazu Street, Katutura(next to A. Shipena Secondary School)

Tel. 061 - 268200Fax 061 - 268201