New Office Works’ canopy uplifts Cheung Sha Wan Promenade
New Office Works has introduced an undulating canopy to the Cheung Sha Wan waterfront promenade in Hong Kong. The structure is intended to offer shade and protection, resembling the aggregation of docked boats commonly seen along the harborfront. Positioned amidst a mix of older and newer developments on the west side of the Kowloon Peninsula, it links residential and commercial zones to the northwest with a wholesale food market to the southeast. As a part of a broader waterfront upgrade, it establishes connections between the pier and promenade and the city through three main pathways: an open-air route leading to the MTR station, a pathway through the neighboring hotel’s central courtyard, and a more secluded path next to the residential complex.
all images by Rory Gardiner
a Design taking its cues from Waterfront Heritage
The design of the canopy draws inspiration from the site’s history, particularly the active cargo offloading and the docking of boats around the pier. Divided into five shifting strips, the canopy allows for varied spatial experiences and promotes natural ventilation through well-placed voids. During the day, sunlight filters through the shelter, creating interesting light and shadow effects. At night, the interior lighting gives it a distinct profile floating above the water.
The canopy is built using a steel framework consisting of cylindrical columns and curved beams. Its highest section is positioned centrally, gradually declining in height on both sides. To avoid duplicating columns along the roof’s edge, the lower roof is hung from the higher one by a system of suspension rods. The upper roof is covered with a standing seam roof featuring grooves that accentuate its curved shape, while satin aluminum panels form the reflective ceiling below, mirroring the rippling water’s surface.
the canopy is inspired by docked boats and historic cargo activity
the design allows natural ventilation and light play
the steel framework is made with cylindrical columns and curved beams
Red shingles and an oversailing roof characterise this sauna, which London studio Built Works has completed in a woodland in East Sussex.
Located on the edge of a family-run farm in the High Weald Area of Outstanding Natural Beauty, the Drying Shed serves guests staying in two nearby cabins.
Built Works has created the Drying Shed sauna in East Sussex
The sauna was commissioned by Architects Holiday, a platform created by the Built Works team that specialises in architect-designed holiday cabins in the countryside.
It is situated in a small clearing within walking distance from the cabins and is reached via woodland paths.
The structure is covered with red shingles
Built Works’s design references the historical agricultural drying sheds of the area, evident in its geometric form and the patterned use of larch shingles.
The rich, red hue of the cladding aims to complement the surrounding woodland while ensuring it is easily identifiable.
A wood-burning stove features inside
“The choice of red adds a subtle, updated twist to aid wayfinding, yet still sits harmoniously within its setting,” said the studio.
“Detailing features at each corner, in a contemporary take on the traditional cladding found on drying sheds,” the studio continued. “Overhanging panels would open and close to aid the drying process.”
The interior is lined with alder wood
The Drying Shed is constructed from a timber frame, insulated with recycled plastic and sheep wool. It is crowned with a corrugated roof that oversails the structure and offers cover from the elements.
Elevated above the ground, the sauna offers views of a stream and the adjacent countryside through a large picture window.
“The sauna is elevated above ground to reduce harm to surrounding habitats and features discrete root-sensitive screw piles for additional stability,” the studio told Dezeen.
“[It is] perched on stones salvaged from an old barn on the site.”
The Drying Shed is elevated above the ground
The interior is lined with alder timber, a choice inspired by trees in the vicinity.
Central to the experience of the Drying Shed is a wood-burning stove. A bench beside it is crafted from the trunk of a silver birch, the top of which has been carved to form a flat, slatted seat that echoes the floor and walls.
Its red colour aims to make it identifiable in the woodland
Built Works was founded in 2020 and has studios in both London and the Lake District. The construction of the Drying Shed was carried out through a live-build workshop involving staff from Built Works and Architects Holiday as part of an annual summer programme.
Other saunas featured recently on Dezeen include one in Devon with blackened-wood cladding and a large square window and a lakeside one alongside an Art Museum in Finland.
Up next in our Timber Revolution series is a look at the Dalston Works apartment complex in London by Waugh Thistleton Architects, which is the world’s largest cross-laminated timber building.
Completed in 2017, Dalston Works is a 10-storey residential development in east London that contains 121 apartments with balconies as well as two ground-level courtyards, retail and restaurant space and an integrated flexible workspace.
Upon its completion, the project became the world’s largest cross-laminated timber (CLT) building, was its uses more of the material by volume – 3,852 cubic metres – than any other building. Dezeen is not aware of any larger CLT buildings constructed since.
Dalston Works is a mixed-use development in east London
It was designed by local architecture studio Waugh Thistleton Architects – a Shoreditch-based timber specialist that has been predominantly working with engineered wood since 2003.
Waugh Thistleton Architects also designed Murray Grove, which was previously profiled as part of Dezeen’s Timber Revolution series.
CLT is a panel material made by gluing at least three layers of wood at right angles to each other, which is significantly less carbon-intensive than other structural materials such as concrete or steel.
The panels are characterised by structural rigidity in two directions thanks to the arrangement of the layers and are cut to size before being assembled on-site.
Dalston Works has external, party and core walls as well as flooring and stairs made entirely from pieces of CLT that were delivered to the formerly neglected brownfield site over 374 days.
It is the world’s largest CLT building
“[CLT] is replenishable, beautiful, healthy, fast and economic,” Andrew Waugh told Dezeen, who co-founded the architecture studio with Anthony Thistleton in 1997.
“Timber is easy to cut and to build with, so the buildings are easy to adapt – so they last longer,” he added.
“This also makes the material easier to use as part of a prefabricated system so that we can make higher quality buildings faster and with better working conditions for those involved.”
Two ground-floor courtyards feature in the design
The development is separated into several boxy volumes, while the CLT frame was clad in traditional bricks chosen to reference the Edwardian and Victorian architecture of nearby warehouses and terraced properties.
“[The brickwork] was important to the client and to the planners,” reflected Waugh. “I am happy with the way it looks but would have preferred a lightweight cladding material.”
“We needed to greatly increase the amount of timber in the structure just to hold the bricks up in the air,” Waugh explained.
The CLT structure is clad in traditional bricks
Despite this, Dalston Works weighs a fifth of a concrete building of its size, according to the studio, which reduced the number of deliveries required during construction by 80 per cent.
Creating a lighter core meant that the project could reach much higher than if it had been constructed in concrete, since the development sits above the underground Elizabeth Line railway.
The project’s CLT frame also has 50 per cent less embodied carbon than a traditional concrete one. This refers to the amount of energy required to produce and form a material or object.
A timber core means that the building weighs less than a similarly sized concrete structure
“There wasn’t a great deal of client motivation or legislative demand for any measures beyond meeting BREEAM and building regulations,” Waugh recalled, referring to standards that limit operational emissions as opposed to embodied emissions.
“My own view is that building regulations are pretty effective – and if you have an efficient, airtight building which is passively designed to suit its location then the operational carbon demand will be pretty low, and you have to assume that we will generate it from renewable energy in the near future.”
“Lots of stuff and complex gear designed to very slightly reduce the energy demand is a bit of a waste of resources. The real issue here is reducing the use of concrete and steel – the carbon savings from doing that are immense.”
According to project engineer Ramboll, more than 2,600 tonnes of carbon dioxide is stored within Dalston Works’ CLT frame.
Nearly six years on from Dalston Works’ completion, Waugh reflected on the significance of the world’s largest CLT building.
“At the time it was an important milestone – to demonstrate that timber is a viable alternative to concrete and steel – and at scale,” reflected the architect. “But I think it’s dangerous to measure a building’s success by its size,” he warned.
Andrew Waugh has called for action from the UK government to encourage more mass timber architecture
Known as a long-time campaigner for the use of mass timber in architecture, Waugh said that he recently wrote a “big piece” to the UK government calling for it to invest more in sustainable architecture practices, explaining that the UK has been “left way behind” compared with various mass-timber projects being created in other parts of the world.
“The UK is behind in terms of timber because we have a government that does not prioritise carbon reduction – and is heavily influenced by lobbying from both construction companies and the manufacturing industry,” said the architect.
“Architects need to start driving demand – seeking out opportunities to design in timber and build a market. Designers need to prioritise carbon reduction in their work and start reconsidering how they think about success in the buildings they design.”
The photography is courtesy of Waugh Thistleton Architects.
This article is part of Dezeen’s Timber Revolution series, which explores the potential of mass timber and asks whether going back to wood as our primary construction material can lead the world to a more sustainable future.
Recycled TV screens cover the walls of the seven-bedroom Hundred Acre Wood house, which architecture studio Denizen Works has created on a site overlooking Loch Awe in Scotland.
Named Hundred Acre Wood, the castle-like dwelling was designed for a couple with six children on former Forestry Commission land with its own private lochan – a small lake.
Denizen Works has created the Hundred Acre Wood house
Denizen Works has lowered the house into a hollow in the landscape, making it appear as though it emerges out from the ground on the north and south elevations.
According to the studio, this aims to give the home a protective quality, with the help of its monumental appearance that references the work of Spanish sculptor Eduardo Chillida.
Its located on former Forestry Commission land with a lochan
“The brief was for a family home for our clients and their six children – as well as an increasing number of grandchildren – that would reflect their personalities and provide a lasting legacy for the family,” project architect Andrew Ingham told Dezeen.
“Conceptually, it was conceived as a sculpted solid, referencing the work of Eduardo Chillida, to heighten the sense of a protective shell that appears as a robust object in the landscape.”
The building has a monolithic form
While referencing the work of Chillida, the form of Hundred Acre Wood has also been developed in response to the home’s environmental context.
Its layout aims to ensure it has the least visual impact on the nearby road, it makes the most of its vantage point above Loch Awe and its rooms align with the movement of the sun.
It references the work of Spanish sculptor Eduardo Chillida
“The plan is narrow on the west elevation, where it was considered more sensitive due to views from the road below,” said Ingham.
“The form responds to the environmental context, key views and the site’s topography.”
Its rough exterior is clad in recycled TV screens
One of the most unusual features of Hundred Acre Wood is its facade, which is covered in recycled and crushed TV screens for a low-maintenance, pebbledash-like finish.
This was developed by Denizen Works as a “take on a traditional Scottish harling” – a rough wall finish that is made from lime and aggregate.
The hall is the home’s centrepiece
“We sourced a decorative glass chipping created from recycled TV screens collected in Scotland which come in a lovely range of blue-greys which we felt was appropriate for the moody Scottish skies,” Ingham explained.
“Our client is also not keen on TVs, so there was an element of playfulness in their use.”
It is naturally lit by an oculus
As the material had not been used on a building before, the studio had to develop prototypes with the construction materials company Sika to test its performance.
“Large sample panels were produced for client sign-off and to help convince the planners that the system would be successful,” added Ingham.
Inside, the focal point of Hundred Acre Wood is a central, double-height hall lit by an oculus in the ceiling.
This was designed to accommodate a five-metre-tall Christmas tree – one of the client’s main requests for Denizen Works.
Living spaces are arranged around the hall
Around the hall are the main living spaces and the seven bedrooms, all arranged to maximise views of the loch and sun throughout the day.
The majority of the interior has a deliberately pared-back finish to retain focus on the client’s furniture collection, but the hall is designed to be more dramatic.
The rooms have views over Loch Awe
“We wanted to use the finishes to create a sense of drama,” said Ingham, referencing the studio’s design for the hall.
“It features a recycled paper ceiling, clay walls with gold mica flecks and a screeded floor with exposed mirror aggregate,” he continued. “A large, gold-lead-lined oculus is situated over the Christmas tree pit and casts a warm glow into the space.”
The interiors of deliberately pared-back
The thick walls of the home are visible in the deep window reveals of each room, bringing the sense of protection granted by its sculptural exterior to the interior.
Finishing details of the house include a ground source heat pump that provides heating and hot water, while a private borehole provides fresh water to the whole house.
As part of the landscape design, reed beds have been introduced to treat wastewater and rainwater, which is sent to the lochan.
The client’s furniture pieces have been used as focal points
Founded in 2011 by Murray Kerr, Denizen Works is an architecture studio with offices in London and Glasgow.
Other recently completed projects by the studio include the Floating Genesis church, which is crowned by a pop-up roof, and a house on the Scottish island of Tiree with a gable-shaped glass wall.
German tech company Open Funk has developed a more sustainable version of a food processor, which is repairable, upgradable and compatible with glass jars that people already have in their homes.
Shortlisted in the sustainable design category of the 2022 Dezeen Awards, the Re:Mix blender works with standard canning jars of any shape or volume, such as those used to hold jams and pickles, as long as they have an 82-millimetre twist-off lid.
Open Funk’s aim was to create a new approach to designing kitchen appliances by stripping back unnecessary components, open-sourcing the design and allowing people to utilise everyday items they already have in their cupboards.
The Re:Mix blender is designed to be compatible with common canning jars
Re:Mix is constructed from recycled and recyclable materials, with speckled panels of reclaimed waste plastic used to wrap the cuboid base, which holds the motor of the food processor.
Much like a Nutribullet, the gadget has a separate blade head designed to be screwed onto the jar containing the food. This is then slotted on top of the motor and controlled via an aluminium knob mounted on the front.
To extend its lifespan, the product was designed to be easily repaired and upgraded – either in Open Funk‘s Berlin workshop or at home with the help of open-source design plans.
Its separate blade head is designed to be screwed onto the jars
The company also developed a closed-loop business model for the blender, which will involve buying back and refurbishing used Re:Mix models.
“The world’s obsession with competition, globalisation and patents got us to the point where the way we make things is causing tremendous harm to our environment,” said Open Funk. “We believe Re:Mix is proof that another way is possible.”
The base of the food processor has a modular design and is held together without adhesives, allowing it to be disassembled with common tools. Its puzzle-like joints have a simplified design that is sturdy and durable, according to Open Funk.
The design is open-source so that anyone can make their version of the product
The speckled panels surrounding the base of the food processor are made in France by melting and pressing waste plastics, before the resulting slabs are CNC milled in Berlin.
Open Funk says it chose to make Re:Mix compatible with 82-millimetre jars as these are widely available across Europe, as well as being large enough to accommodate the blades and to fit most people’s hands for rinsing.
A QR code on the back of the blender’s base leads to a repair guide, video tutorials and a product passport that helps users to repair and upgrade the product themselves.
Open Funk only ships to the European Union, which the company says was an intentional decision to guarantee repairability, lower the ecological footprint from shipping and bypass the work of having to engineer the product for international standards.
Instead, the company hopes to inspire designers around the world to adapt its product for their own markets.
“We hope to see other hackers, makers and entrepreneurs take the open-source blueprints of Re:Mix and build their own local versions in their own regions,” Open Funk co-founder Paul Anca told Dezeen.
It has a modular design that is easy to take apart for repairs and upgrades
“Not only would this create a platform for decentralised production with low emissions but the end products will be reflections of local customs, taste and materials,” he continued.
“That’s a much more creative expression than the current one-size-fits-all approach we see in the industry.”
Re:Mix is shortlisted in the sustainable design category of the 2022 Dezeen Awards, where it is up again projects including the K-BriqTM – a brick made entirely of construction waste – and a bespoke furniture collection made from firehoses by Local Works Studio.
We all know there is a considerable lack of affordable housing in the U.S. and that addressing it effectively has been challenging. Now that many states and municipalities are altering their zoning to allow Accessory Dwelling Units (ADUs), there is a new opportunity to expand truly affordable rental housing – building low-cost zero energy ADUs – sometimes referred to as in-law apartments, garage apartments, attic apartments, tiny homes, or casitas. But how to make them truly affordable?
Small ADUs are Affordable
By their very nature, ADUs will cost less to rent because they are smaller, and building them uses fewer materials. This is even more likely in an above the garage, basement, or attic ADU where existing structural elements can be used. They also have no land costs because they are built on an existing lot or above an existing garage. And there are no landscaping costs other than restoring any construction disruption. Sewer, water, and electricity are close at hand. And, if they are zero energy ADUs, they will need no gas hook-up. More importantly, they will have no, or almost no, energy bills for their residents.
Zero Energy Bills
There are two legs to affordability. One is the rent – the other is the monthly utility bill. The second one is almost always overlooked when considering affordable housing, but high energy bills can play a devastating role in making an ADU rental unaffordable. Zero Energy ADUs solve that problem and offer a more truly affordable rental. The challenge is how to get to zero at least cost, so the rent can be kept low.
Cost Cutting Zero ADU Construction
The first step in low-cost zero energy construction is conducting energy modeling on the planned structure. Energy modeling will help select the lowest cost mix of energy-saving measures such as insulation and air sealing, energy-saving equipment, and solar. For example, energy modeling and price comparisons will quickly determine whether it is more cost-effective to use a heat pump water heater or add some additional panels and use a standard water heater – or whether to use insulation with a higher or lower u-value.
There are other potential savings related to the smaller size of an ADU. Windows are expensive. Locating them to optimize light and views, and eliminating or reducing them where they are not needed, may allow smaller glazed areas. Since mini splits can be ductless, there is no need for ductwork. Most ADUs can be heated and cooled with one small unit, which is quick and easy to install. Since heat pump HVAC systems should never be oversized, smaller ones are usually the best choice.
In small homes, such as ADUs, energy or heat recovery ventilation systems can be installed without ducts, using a Lunos e2 through-the-wall HRV or a Panasonic Whisper Quiet ERV to provide fresh filtered air. The size of the water heating system can be tailored to a smaller number of inhabitants. A smaller 30 or 50-gallon heat pump water heater is an excellent but more expensive option. Using a small well insulated standard electric water heater with added solar panels may be less costly. An even more economical option might be using one or two-point of use tankless electric water heaters – one in the bath and one in the kitchen – and adding sufficient solar to cover its energy use.
An ADU Solar Advantage
Another significant potential savings with constructing a stand-alone ADU is a second chance to install solar on the main property. If the original home does not have a good solar orientation, it may be possible to orient and design an ADU with enough solar for both the original home and the ADU. Any ADU-related shed or garage can be designed to optimize solar exposure. Large roof overhangs to shade the southern or western sun to avoid overheating can also expand the solar area. Or depending on orientation, sufficient solar can be installed on the main home to supply both the main house and the ADU – or some panels can be installed on the sunniest areas of each roof. In any case, optimizing the number of solar panels will lower the cost of ownership and renting.
Small ADUs can Live Large
The key to a successful small ADU is designing it for large living. Building inexpensive non-conditioned storage spaces outside of the conditioned ADU, either in an attached or stand-alone shed or added to a connected or stand-alone garage, is affordable and leaves room for ample storage outside and living inside. Smart kitchen/dining areas design can provide all the amenities in a small space. Creating accessible storage spaces under stairs and over cupboards optimizes the use of space, as do multipurpose rooms like office-bedroom spaces.
Our Experience
We decided to add ADUs to our two small rental homes on two different properties in Bend, Oregon, where the city changed the code to allow ADUs. We conducted energy modeling to determine the least-cost path to zero. We sealed the building envelope using Aerobarrier and insulated it well. We used a small heat pump mini split for HVAC and a small heat pump water heater, used one Panasonic Whisper Quiet ERV in the bath and one in the kitchen, and installed energy-efficient electric appliances, including an induction stove. We added generous unconditioned storage areas outside of each unit. Because neither of the existing small homes had a good solar orientation and the ADUs did, we added enough solar on each of the ADUs to power both the ADU and the original house on each lot. So they both became zero energy homes.
Perfect for Low Income Housing
We can profit from rents while the tenants enjoy no energy bills. We have rented out two units, with two more on the way, to people with low incomes, referred by local non-profit organizations, providing them with affordable small, well-designed living spaces with no energy bills.
A sweeping, tiled roof informed by the surrounding mountain ranges tops the Yong’an Community Hub in China, which has been designed by students from Tongji University in Shenzhen with architecture studio Archi-Union.
Referencing local structures and involving residents in its construction process, the rammed-earth, courtyard-style building provides a gathering space and residence for the Yong’an village’s more isolated upper area.
Shortlisted in the civic building category of Dezeen Awards 2022, Yong’an Community Hub forms part of an ongoing social welfare programme funded by Tongji University and led by Philip F Yuan, principal of Shanghai-based studio Archi-Union.
Archi-Union worked with Tongji University to create the community hub
“The villagers from the upper village often suffer from inaccessibility to transportation, and are living in strained circumstances,” said the project’s team.
“The majority have no space to interact with one another other than their working space, therefore building a community centre for the upper village [became] the main goal of the volunteer activity.”
Bordered by stone walls, the main building sits at the north of the site, with a smaller toilet block on the opposite side of a large courtyard. Both were built using rammed earth partially made from the red sandstone found near the site.
The building features rammed-earth walls
A run of wooden doors allows the main building to be almost completely opened to the courtyard, while a thin, letterbox-style window in its northwest corner frames views back towards the village.
The steel-framed, curving roof contrasts these traditionally-built rammed earth structures, using parametric design methods to create an undulating arc around the courtyard and minimising the use of non-standard components to make construction easier.
This roof shelters what the team describes as a “floating corridor”, an area of covered seating space that provides an area to dwell, watch performances or take in expansive views of the surrounding valley landscape.
“While retaining the functionality of the interior spaces, we tried to maximise the open public space as much as possible… from funerals to weddings or even daily socialising, the openness of space becomes the top priority to [the villagers],” said the team.
“The ‘floating corridor’ became a continuous yet fluid element that held the spaces together…to accommodate the low height of the entrance the roof was lowered, forming a starting point that ends when it meets the mountain slope.”
An undulating canopy wraps around the centre
Other projects on the shortlist for the civic project category of Dezeen Awards 2022 include a hospital in Myanmar by German practice A+R Architekten, which also drew on materials and typologies local to the area for its design.
You’re invited! Join Architizer for an engaging live webinar presented by Roderick Bates, Head of Integrated Practice at Enscape, and learn how to successfully implement real-time visualization at every stage of design, while also creating a more inclusive design process.
Hosted by Editor in Chief Paul Keskeys, Architizer’s first webinar on architectural visualization is one not to be missed! Hit the button below to sign up for the talk, which will take place at 12pm EST on Tuesday, March 29th:
BIM/CAD software often lacks a visually intuitive interface, making it too far removed from reality to understand on a level sufficient to make rapid, informed design decisions. Real-time visualization is the missing link that bridges the gap between a BIM/CAD interface and a constructed project, helping both designers and their clients to envision what a design will actually look like when built.
Decision making, BIM model quality assurance, performance analysis, and coordination all benefit from bringing real-time visualization to the BIM/CAD workflow, and Roderick will show how to do this best.
By attending this webinar, you’ll learn how to:
Utilize real-time visualization to increase client and stakeholder understanding of the project design at every phase
Leverage real-time visualization to conduct individual and collaborative BIM/CAD model quality assurance workflows
Identify opportunities where real-time rendering can greatly reduce the time required for critical decision making
About Roderick
Throughout his career, Roderick has sought out and developed solutions to environmental challenges related to the design, construction, and operations of buildings. As the Head of Integrated Practice at Enscape, he is responsible for researching industry and market trends which are shaping the way Enscape customers work. Leveraging that industry knowledge, Roderick collaborates with Enscape Product and R&D leaders to assess new product development opportunities that will shape the future of building design. Previously, as a Principal at Kieran Timberlake, Roderick led the efforts to develop and commercialize software and hardware tools used by the greater the AEC community to improve the environmental and operational performance of buildings.
About Paul
Paul Keskeys is Editor in Chief at Architizer. An architect-trained editor, writer and content creator, Paul graduated from UCL and the University of Edinburgh, gaining an MArch in Architectural Design with distinction. Paul has spoken about the art of architecture and storytelling at many national industry events, including AIANY, NeoCon, KBIS, the Future NOW Symposium, the Young Architect Conference and NYCxDesign. As well as hundreds of editorial publications on Architizer, Paul has also had features published in Architectural Digest, PIN—UP Magazine, Archinect, Aesthetica Magazine and PUBLIC Journal.
We all know there is a considerable lack of affordable housing in the U.S. and that addressing it effectively has been challenging. Now that many states and municipalities are altering their zoning to allow Accessory Dwelling Units (ADUs), there is a new opportunity to expand truly affordable rental housing – building low, cost zero energy ADUs – sometimes referred to as in-law apartments, garage apartments, attic apartments, tiny homes, or casitas. But how to make them truly affordable?
Small ADUs are Affordable
By their very nature, ADUs will cost less to rent because they are smaller, and building them uses fewer materials. This is even more likely in an above the garage, basement, or attic ADU where existing structural elements can be used. They also have no land costs because they are built on an existing lot or above an existing garage. And there are no landscaping costs other than restoring any construction disruption. Sewer, water, and electricity are close at hand. And, if they are zero energy ADUs, they will need no gas hook-up. More importantly, they will have no, or almost no, energy bills for their residents.
Zero Energy Bills
There are two legs to affordability. One is the rent – the other is the monthly utility bill. The second one is almost always overlooked when considering affordable housing, but high energy bills can play a devastating role in making an ADU rental unaffordable. Zero Energy ADUs solve that problem and offer a more truly affordable rental. The challenge is how to get to zero at least cost, so the rent can be kept low.
Cost Cutting Zero ADU Construction
The first step in low-cost zero energy construction is conducting energy modeling on the planned structure. Energy modeling will help select the lowest cost mix of energy-saving measures such as insulation and air sealing, energy-saving equipment, and solar. For example, energy modeling and price comparisons will quickly determine whether it is more cost-effective to use a heat pump water heater or add some additional panels and use a standard water heater – or whether to use insulation with a higher or lower u-value.
There are other potential savings related to the smaller size of an ADU. Windows are expensive. Locating them to optimize light and views, and eliminating or reducing them where they are not needed, may allow smaller glazed areas. Since mini splits can be ductless, there is no need for ductwork. Most ADUs can be heated and cooled with one small unit, which is quick and easy to install. Since heat pump HVAC systems should never be oversized, smaller ones are usually the best choice.
In small homes, such as ADUs, energy or heat recovery ventilation systems can be installed without ducts, using a Lunos e2 through-the-wall HRV or a Panasonic Whisper Quiet ERV to provide fresh filtered air. The size of the water heating system can be tailored to a smaller number of inhabitants. A smaller 30 or 50-gallon heat pump water heater is an excellent but more expensive option. Using a small well insulated standard electric water heater with added solar panels may be less costly. An even more economical option might be using one or two-point of use tankless electric water heaters – one in the bath and one in the kitchen – and adding sufficient solar to cover its energy use.
An ADU Solar Advantage
Another significant potential savings with constructing a stand-alone ADU is a second chance to install solar on the main property. If the original home does not have a good solar orientation, it may be possible to orient and design an ADU with enough solar for both the original home and the ADU. Any ADU-related shed or garage can be designed to optimize solar exposure. Large roof overhangs to shade the southern or western sun to avoid overheating can also expand the solar area. Or depending on orientation, sufficient solar can be installed on the main home to supply both the main house and the ADU – or some panels can be installed on the sunniest areas of each roof. In any case, optimizing the number of solar panels will lower the cost of ownership and renting.
Small ADUs can Live Large
The key to a successful small ADU is designing it for large living. Building inexpensive non-conditioned storage spaces outside of the conditioned ADU, either in an attached or stand-alone shed or added to a connected or stand-alone garage, is affordable and leaves room for ample storage outside and living inside. Smart kitchen/dining areas design can provide all the amenities in a small space. Creating accessible storage spaces under stairs and over cupboards optimizes the use of space, as do multipurpose rooms like office-bedroom spaces.
Our Experience
We decided to add ADUs to our two small rental homes on two different properties in Bend, Oregon, where the city changed the code to allow ADUs. We conducted energy modeling to determine the least-cost path to zero. We sealed the building envelope using Aerobarrier and insulated it well. We used a small heat pump mini split for HVAC and a small heat pump water heater, used one Panasonic Whisper Quiet ERV in the bath and one in the kitchen, and installed energy-efficient electric appliances, including an induction stove. We added generous unconditioned storage areas outside of each unit. Because neither of the existing small homes had a good solar orientation and the ADUs did, we added enough solar on each of the ADUs to power both the ADU and the original house on each lot. So they both became zero energy homes.
Perfect for Low Income Housing
We can profit from rents while the tenants enjoy no energy bills. We have rented out two units, with two more on the way, to people with low incomes, referred by local non-profit organizations, providing them with affordable small, well-designed living spaces with no energy bills.
