Landlord Tech, what the real estate industry describes as residential property technology, is leading to new forms of housing injustice. Property technology, or “proptech,” has grown dramatically since 2008, and applies to residential, commercial, and industrial buildings, effectively merging the real estate, technology, and finance industries.

By employing digital surveillance, data collection, data accumulation, artificial intelligence, dashboards, and platform real estate in tenant housing and neighborhoods, Landlord Tech increases the power of landlords while disempowering tenants and those seeking shelter.

By Landlord Tech, we mean technical products and platforms that have facilitated the merging of the technology and real estate industries in novel ways, particularly as they impact tenant housing. Our research has led to two major categories of what we are calling Landlord Tech: surveillance and speculation, both of which are tied up in gentrification.

Read more: Landlord Tech.

Image: Erik Henningsen’s painting Eviction held by the National Gallery of Denmark, 1892.

Who to call when you need your building “hand-demolished”? To the general public, “Amish” often equates to handcrafted – meaning hand-milked cows, handmade quilts, hand-built furniture, and the like (whether that perception is always accurate is another question).

And in that spirit, one Tennessee city found that an Amish hands-on approach was exactly what they needed to remove a historic structure. The Clarksville Leaf-Chronicle reports that an Amish crew of workers has been deconstructing the city’s 140-year-old Hodgson/Dabbs building, brick-by-brick.

Read more: Amish Hand-Demolish Building in Tennessee, Amish America, June 27, 2019. Image by Henry Taylor for the Leaf Chronicle.

Oula Lehtinen – CC BY-SA 3.0

Approximately 5.7 million solid-walled houses exist in England, comprising 25% of the housing stock. Most were built between 1750 and 1914. Research shows that their energy efficiency has been underestimated for decades.

The English Housing Survey (EHS) defines solid-wall construction as a building where external load-bearing walls are made of brick, block, stone or flint with no cavity. In England, the shift to the use of solid-wall brick construction began during the great rebuilding from mid-16th century.

For the present English housing stock, the overwhelming fraction of solid-walled dwellings, constructed mostly of brick, derives from the expansion of population from the mid-18th century to the beginning of the First World War. Solid walls continued to be the most common construction for the domestic sector until the British housing boom of the 1920s and 1930s.

Wall Thickness

The most widely used estimate of the U-value (the measure of thermal conductivity) of a UK solid-wall property is 2.1 Wm−2 K−1. However, there is growing evidence that solid-wall U-values are much lower than previously assumed. Several studies in recent years have found that the mean or median U-values measured for solid-walled construction were around 1.3–1.4 Wm−2 K−1. There are two reasons for this large discrepancy.

First, standard solid brick wall U-values are based on an assumed wall thickness of 220 mm brick and approximately 12 mm of dense plaster. Modern bricks are 220 mm long and so this assumption would be logical for a modern brick wall. However, the thickness of 220 mm was used as a conservative estimate to capture variation in brick production. Following the Great Fire of London in 1666 brick properties over two stories were required to be constructed with walls that were more than one brick thick.

The required thickness of load-bearing masonry walls in England therefore increases with the height of the building. While two-storey buildings can be built with walls of just over 200 mm thickness, three-storey buildings require a minimum of 300 mm and four-storey buildings require walls of at least 400 mm. Consequently, it is obvious that the mean thickness of solid walls in the UK housing stock is likely to be greater than the nominal 220 mm of a single brick wall.

Air Cavities

Secondly, so-called ‘solid walls’ are in fact often not completely solid. Brick walls can be built up in a variety of different patterns, but are typically constructed with a mixture of brick types, with some going straight through the full depth of the wall, known as headers, and some laid side by side, known as stretchers (see image above). In order to allow walls to be constructed with a regular type of mortar bond, the total width of two adjacent stretchers is less than the length of a header by the width of a mortar joint, which is typically 5–10 mm.

Although some mortar will intrude into the space as snots from joints between stretchers, the practical constraints of bricklaying mean that this gap is often not filled with mortar. There is a high probability that solid-wall segments built with stretchers contain air gaps. If stretchers are assumed to comprise 50–80% of the wall surface, with air gaps of the order of ≈10 mm, then a straightforward calculation with identical assumptions regarding brick density etc. yields U-value estimates in the range of 1.65–1.8 W−1 m2 K.

‘Solid’ stone walls may also contain residual air cavities for similar reasons. Walls built with stone are often thicker overall than single-brick walls and often employ rubble-filled cores. It is almost certain that there are voids within these cores that would increase the thermal resistance of the element relative to that of a completely solid wall.

Consequences

Among the many implications for policy, discrepancy between real-world U-values and U-values assumed in energy modelling and standard UK building assessment protocols suggests that standard solid-wall U-values may be inappropriate for energy certification or for evaluating the investment economics of solid-wall insulation.

Reducing the represented U-value of solid walls in the stock from 2.1 to 1.3 Wm−2 K−1 reduces the estimated mean annual space heating demand by 16%, and causes approximately one-third of all solid-wall dwellings to change Energy Performance Certification (EPC) band.

Source:
Li, Francis GN, et al. “Solid-wall U-values: heat flux measurements compared with standard assumptions.” Building Research & Information 43.2 (2015): 238-252. http://www.tandfonline.com/doi/full/10.1080/09613218.2014.967977

Malawi home built with rammed earth and thatch roof in Chizogwe village. Picture: Jon (Twingi) Sojkowski

I am a registered architect and I have a passion for African vernacular architecture. I recently (Sept. 2014) traveled to Malawi to document the vernacular architecture in the entire country. 4,700 pictures are on the web page.http://www.malawiarchitecture.com/

I also wanted to share with you my latest project… a data base on African vernacular architecture. This project was started because of the lack of information available on line. The data base includes images from every African country. Here is the link to the site:

http://www.africavernaculararchitecture.com/

The goal of the project is to have people, who live or work in an Africa country, submit pictures of vernacular structures to the data base to share with the world. Full credit is given for every picture submitted. For too long, African vernacular architecture has been a topic that has been both under-documented and, unfortunately, ignored. People say there needs to be documentation but yet nothing is done. Whether this is due to difficulties in obtaining funding or just apathy, the fact remains that very little data can be found online.

House with porch in Malawi. Picture: Jon (Twingi) Sojkowski

Architecture is as much of a part of a countries culture as is language, music or art. African vernacular architecture is disappearing. I witnessed that fact in Malawi. There are many reasons why vernacular materials and construction techniques are being abandoned in favor of western ones. One main reason is the lack of documentation, especially finding information on line.

I am hoping you could share the project with your readers, the more awareness, the better the chance to convince people to submit pictures to the data base. There is no other resource for African vernacular architecture like the data base: there is no organization gathering information, there is no active research, there is no voice for it. I will gladly answer any questions that you might have about the project.

Cheers,

Jon (Twingi) Sojkowski

Building on statistical analysis of the built fabric of three major American cities [San Francisco, Seattle, and Washington, D.C.], the research demonstrates that established neighborhoods with a mix of older, smaller buildings perform better than districts with larger, newer structures when tested against a range of economic, social, and environmental outcome measures.”

“Older, Smaller, Better. Measuring how the character of buildings and blocks influences urban vitality“, National Trust for Historic Preservation, May 2014. Via Lloyd Alter.

There are quite some photo reportages about factories, and this one in particular is noteworthy: a forgotten flour mill with part of the machinery still in excellent condition.

The author does not reveal any location for any of the buildings on the blog.

The ‘Sustainable Urban Dwelling Unit’ (SUDU) in Ethiopia demonstrates that it is possible to construct multi-story buildings using only soil and stone. By combining timbrel vaults and compressed earth blocks, there is no need for steel, reinforced concrete or even wood to support floors, ceilings and roofs. The SUDU could be a game-changer for African cities, where population grows fast and building materials are scarce.

In “Tiles as a substitute for steel“, we highlighted the medieval art of the medieval timbrel vault, which allowed for structures that today no architect would dare to build without steel reinforcements. The technique is cheap, fast, ecological and durable. Shortly after the article was published in 2008, the timbrel vault made a comeback with two rather spectacular buildings: Richard Hawkes’ Crossway Passive House in England, and Peter Rich’s Mapungubwe Interpretation Centre in South Africa.

The cardboard formwork technique described last week promises to bring even more dramatic architecture, but at least as interesting is the news that the catalan vault is now also applied to a much more modest form of housing: the Sustainable Urban Dwelling Unit (SUDU), a low-cost family dwelling built in Ethiopia.

The Sustainable Urban Dwelling Unit (SUDU).

Though less spectacular at first sight, it could form the proof that even megacities can be constructed without the use of steel, concrete or wood. The double-story building, which was completed in last summer, is entirely made from soil and presents an economical and ecological solution to many of Africa’s most urgent problems. The SUDU stands in Addis Ababa, Ethiopia, a country with a population of more than 80 million (growing at an average 7 percent per year). The building is a joint project of the Swiss Federal Institute of Technology (ETH Zurich) and the Ethiopian Institute of Architecture, Building Construction and City Development (EiABC).

The SUDU combines past technologies from different continents, resulting in a new approach to low-tech construction adapted to specific local conditions. In the Mediterranean region, where the timbrel vault originated, the tiles have traditionally been made from fired clay. In the SUDU, the construction technique is united with the African tradition of cement-stabilized, soil-pressed bricks, which use locally available soil. This technique is called compressed earth block (CEB) construction. The SUDU has been built largely following the same techniques used for the Mapungubwe Centre in South Africa.

Urban housing

The SUDU was designed to achieve both environmental and economic sustainability. Because Ethiopia has few material and financial resources, the design is aimed at eliminating the reliance on imported, expensive and energy-intensive building materials such as steel and concrete. More unusual is that the building also excludes the use of wood, for the simple reason that wood is equally scarce in the country. The entire structure is made from locally available construction materials – and in the case of Ethiopia, these are very few: soil and stone.

The Sustainable Urban Dwelling Unit (SUDU).

One of the most challenging present problems for Africa (and throughout the developing world) is the tremendous deficit in housing for the urban poor. In Ethiopia, this is reflected in the ubiquitous informal housing, comprising perhaps 80% of the built environment of its capital, Addis Ababa. The most common vernacular construction method – construction with Eucalyptus wood and mud – is an economically and environmentally sustainable method of construction, but the problem of such constructions is that they are limited to one story – putting a huge strain on available land.

Thus, this vernacular technology has been more recently replaced by large urban housing projects of reinforced concrete, heavily subsidized by the government. These massive edifices of concrete and steel neither offer a model for frugal, environmentally or economically sustainable construction, nor do they offer a low-cost alternative to housing because they are too expensive to construct. The result is that more and more people are forced to be living on the streets. Whether it is the United States or Ethiopia, governments seem to prefer homeless people over shanty-towns.

The Sustainable Urban Dwelling Unit (SUDU).

In poorer areas of Addis Ababa, dwellings are often constructed from corrugated metal. These dwellings cannot be expanded upon for multi-story construction, yet sprawl outward, consuming limited resources including wood, expensive imported materials, and land.

Urban density

The SUDU is an exploration of a “medium ground” between single story informal dwelling and massive scale urban density, as studies have shown that even two-story buildings dramatically impact urban density. As the example of Tokyo shows, a megacity can be largely based on double-story buildings. Because the other aim is to build using only locally available materials, and wood reserves are scarce, the goals of SUDU were to build two stories in soil – a significant challenge without the aid of steel, concrete or milled lumber. Multiple-story soil architecture has a long tradition in Africa, though none of it has been constructed without wooden beams.

Building multiple stories in soil is a significant challenge without the aid of steel, concrete or lumber

As soil and stone have limited tensile capacity, building with these materials demands compression-only structural solutions. For walls carrying dominantly vertical loads, this criterium is easily satisfied. However, once a space must be spanned, beam elements – which work in bending – are typically required. A beam, as a structural system, demands that its section can accomodate tension and compression forces, which is not possible when building in stone or soil only.

The Sustainable Urban Dwelling Unit (SUDU) under construction.

By adapting local soil knowledge to the production of soil stablized tiles, however, it is possible to introduce the technology of timbrel vaulting to allow floor and roof systems of pure compression in multiple story buildings. Ethiopia has a rich soil, which contains high levels of clay particles. Almost all excavated material in the city of Addis Ababa is a possible source for the material needed to build new structures. The SUDU uses rammed earth techniques to construct the first level of the building, with a 60 cm wide wall structure. The ceilings and floors and the building are done using a tiled vauling technique using sun-dried tiles (first floor) and loam (for the roof) made from the very same soil.

Contrary to most other vaulting techniques, the catalan vault does require little to no formwork, again bypassing the need for wood.

Model for low-cost housing

Apart from the ecological and financial benefits, the construction technique used in the SUDU offers additional advantages. By drawing upon traditional methods, it engenders pride and social cohesion within the local community. And by using only locally available materials, it provides local jobs, introduces new skills and stimulates self-sufficiency. Through the economic benefits, the SUDU may become a model low-cost housing unit for the urban poor in Africa. It is meant to be a showcase to convince decision makers, economists, urban planners and architects to rethink traditional building methods and find new ways to build a town or even a city.

The construction of the SUDU was led by Lara Davis, who published a blog where the building process is documented from A to Z. There is also a movie. The BLOCK Research Group of the Swiss Federal Institute of Technology (ETH Zurich) has a webpage that links to all the research papers on the construction method. A book was presented November 25. Also of interest is a special architectural 2010 issue of the ADTF Journal published by the African Technology Development Forum. Several articles deal specifically with timbrel vaulting building methods, and outline some of the remaining challenges:

• “Tile vaulted systems for low-cost construction in Africa“.
• “Design and Construction of the Mapungubwe National Park Interpretive Centre, South Africa“.

Previously:

• Tiles as a substitute for steel: the art of the timbrel vault
• Timbrel vaulting in South Africa by Peter Rich
• Timbrel vaulting using cardboard formwork
• Engineering for the ecological age: lessons from history
• Building with mud and steel frames
• Building with pumice
• How to build a reciprocal roof frame
• How to build an earthbag dome
• How to build a medieval city
• Birch bark sauna
• Innovation and tradition: the complete works of Hassan Fathy online
• Why older buildings are more sustainable
• The solar envelope: how to heat and cool cities without fossil fuels

Find pictures and the research paper here or see the summary below.

Timbrel vaulting (also known as ‘Catalan vaulting’ or ‘thin-tile vaulting’) offers a sustainable roof and floor construction method because it uses fewer building materials than conventional techniques. Timbrel vaulting employs the use of good structural form to achieve a minimal shell thickness and requires no formwork. The new tools designed by the Swiss researchers aim to combine these advantages with a whole new range of complex shapes, which they call ‘freeform shells’:

“This research project presents important advances in timbrel vaulting, made possible through innovation in form finding, guidework systems and construction methods. A full-scale prototype has been realized with the application of new research in the following areas: newly developed structural design tools based upon the Thrust Network Approach (TNA), which allow one to generate novel shapes for funicular (i.e. compression-only) structures; an efficient cardboard box guidework system, which allows for a vaulted surface to be described in an accurate manner in space for the mason; and adaptations upon traditional timbrel vaulting techniques, which have introduced strategies for continuous tiling patterns, shell thickening, and sequencing for structural stability during construction.”

Matthias Rippmann designed both the prototype and the software tool, which is free to download:

“RhinoVAULT is software that allows for the intuitive design of compression-only shapes, offering a maximum control of the geometry. This software is written particularly for shaping unreinforced masonry vaults, but can also be used for designing efficient freeform shells. Based on the Thrust Network Approach (TNA), which uses a force network as discretization of the shape, it is possible to internally redistribute forces within the network using force diagrams. This enables the user to generate exciting forms far beyond typical ‘hanging-net’ morphologies.”

Contrary to the traditional timbrel vaulting techniques, these new forms require a continuous formwork system. While this approach seems to negate the inherent material and labour efficiency of thin-tile vaulting, the researchers introduce a formwork system using cardboard that still possesses the material economy of the traditional Catalan shell:

“The cardboard formwork implemented in this project is fabricated with 2-D CAD-CAM cutting and gluing processes and is assembled on site. The system’s rapid fabrication, lightweight transportation, and speed of erection and de-centering dramatically reduce the material and labour-based costs of construction. An inexpensive and potentially reusable/recyclable material, this lightweight cardboard formwork extends the viability of thin-tile vaulting to freeform construction.”

The formwork system is expandable, essentially composed of simple boxes supported by stacked shipping palettes. Using palettes for the first rough approximation of the final vault shape offers several advantages: it reduces the volume of cardboard to be used, it facilitates easy access during construction as the palettes can be arranged in step-like configuration, and it decreases the size of the boxes, ensuring that the unrolled cutting pattern of boxes fit to the limited machine-size of the CNC cutting machine.

A particular challenge is de-centering, which is the process of removing the formwork from the surface of the shell. This is a sensitive process, because the entire formwork should be removed equally and simultaneously to avoid dangerous asymmetric loading cases from below. Such asymmetric loading would induce bending in a compression-only structure and potentially cause cracking and failure. To prevent this, the researchers developped a special mechanism:

“The entire formwork sits on top of a series of sealed plastic tubes containing cardboard spacers. Each spacer, which consists of a folded stack of cardboard sheets, taped together, supports the corners of typically four palettes. After the vault is completed, the tubes are filled with water, saturating the cardboard, causing it to compress under the load of the palettes and effectively to lower the formwork.”

The construction (and eventual destruction) of the prototype, built by Lara Davis, is documented in a time-lapse video.

Davis L., Rippmann M., Pawlofsky T. and Block P. Efficient and Expressive Thin-tile Vaulting using Cardboard Formwork, Proceedings of the IABSE-IASS Symposium 2011, London, UK. (PDF).

Picture below: testing the strength of the structure.

Previously:

• Tiles as a substitute for steel: the art of the timbrel vault
• Timbrel vaulting in South Africa by Peter Rich
• Engineering for the ecological age: lessons from history
• Building with mud and steel frames
• Building with pumice
• How to build a reciprocal roof frame
• How to build an earthbag dome
• How to build a medieval city
• Birch bark sauna
• Innovation and tradition: the complete works of Hassan Fathy online
• Why older buildings are more sustainable

“The University of Tennessee Extension maintains a collection of over 300 building and equipment plans, and all are now available in electronic format for download. The plans are primarily intended for use in Tennessee, but many are appropriate for other locations as well.

The plans came from many sources. Some were developed in The University of Tennessee Extension Biosystems Engineering and Soil Science Department, but most were developed in a cooperative effort with the United States Department of Agriculture and the Cooperative Farm Building Plan Exchange. The Plan Exchange no longer exists, but the plans remain on file and are available.”

Via The Survivalist Blog.

“In the late 14th century, England’s King Richard II commissioned a new building, College Hall, at Oxford University. The carpenters who built College Hall knew that the massive oak beams spanning the great hall’s ceiling would probably need to be replaced in a few hundred years, so next to the building, they planted a row of oak seedlings from the trees they used for the beams. Sure enough, the beams needed to be replaced about 300 years later, and the new carpenters had mature oaks right there, ready to be milled and turned into new beams.”

Greening Main Street Buildings (more). The picture shows an example of a recessed entryway – a characteristic common to many traditional commercial buildings that helps prevent hot or cold air from rushing inside when a door is opened.

Once more, hat tip to Lloyd Alter.