Energy Certificates, also called Energy Passports, are documents that profile the energy performance of existing and new buildings within the European Union. The program was initiated as part of the EU Directive on the Energy Performance of Buildings in January of 2006 and will be mandatory throughout the member countries. The goal is to provide greater transparency of energy efficiency to building renters, buyers, owners and policy makers and thereby encourage a market driven approach to energy efficiency.

“Every car-owner knows exactly how much gas their car uses… but the high energy costs of an apartment or house are mostly unknown.”

“We are hoping that this [energy certificate program] will finally help make rents [costs] a little more transparent.” – Ulrike Leidinger, energy consultant at the Consumer Center in Aachen Germany – Deutsche Welle Magazine

Certification is based on an assessment, an inspection, made by building energy performance experts. The assessment is not specific to the active building systems and includes boilers, heat pumps, heating elements, as well as windows, wall insulation, air infiltration and a myriad of elements that influence the energy efficiency of a building. Computer software is then used to analyze the measured data and assign a grade ranking based on a number of considerations. The EU Directive mandates that local and regional factors are considered to promote an ‘apples to apples’ comparison for consumers. Prices for an inspection currently range from $213 to $563 for a two family house in Aachen, Germany, but are expected to rise once the program is fully implemented.

All this is supported because the EU Directive ‘identifies energy efficiency in the building sector as a top priority.’ An introduction to the directive notes that European leaders believe there is a building energy savings potential of 28%, which would reduce EU final energy use by about 11%. Interestingly, researchers assert that Europe wastes up to 20% of its energy and the hope is that efforts such as the Energy Certificate program can help recapture some of that lost energy. It is of course being done in the name of ‘protecting the environment and guaranteeing a stable supply of energy for [our] children.’

A directive of this scope is of course very broad. The Energy Certificates portion is actually one of five ‘themes’ implemented by the EPBD Directive. These themes include: Certificates, Inspection, Experts, Calculations, and EP Requirements. Each is designed to affect the energy performance of buildings in significant ways and focus on everything from the design process to simulation techniques to measurement to maintenance to building a body of qualified experts who can work on these buildings. The directive also sets minimum energy performance requirements which encourage the use of renewable energy , combined heat and power (CHP), district heating and cooling, and heat pump systems depending on the application.

The Energy Certificate program is remarkable because it attempts to expose and connect the often obscure world of real estate, utility use, and building efficiency. I propose that it does for buildings what the Nutrition Facts label did for food in the United States. That is, it empowers consumers to educate themselves about the characteristics of the buildings they occupy. The Energy Certificate itself does not have any negative consequences for buildings beyond the small inspection fee. The benefit is that it allows for a fair comparison of similar buildings within a given region so that consumers have a more informed choice. The market can decide if people are willing to live and work in buildings that have a high energy footprint. Who wants to live in a building that has high monthly energy bills? Would a realtor not say to the building owner that the energy performance needed an upgrade in the same way they discuss ‘curb appeal’, ‘granite countertops’ and number of garage parking spaces. Information is power and in concept that is what this program requires.

It must be noted that the USGBC has begun putting ‘Building Facts’ on their recently completed project profiles. Also take a look at the German Passive House Building Standard for more on super efficient buildings.

For more information on Energy Certificates visit the EU EPBD Energy Certificates website. Deutsche Welle also has a great article on the program as it was applied and tested in Aachen, Germany.

Energy in = energy out. Only the format changes. Now that is sustainable.

greenPIX, ‘the Zero Energy Media Wall,’ uses architecture and technology to absorb, store, amplify, translate, and display data, both natural and manmade, in an organic system that responds dynamically to the local environment. Creative programming adds even more layers to the already rich stream of data being presented and allows passersby to experience the site in terms of space and time through both their own eyes or the minds of the selected artists. Media is displayed on a gigantic screen which uses 2,292 pixels of LED lights and translucent glass. The entire presentation comes with a zero net consuming energy footprint thanks to a glazing-integrated system of perforated photovoltaic cells and a battery storage system. The result is a public art installation that creates awareness of the local environment in both appearance and functionality; sustainability is more than facade deep for greenPIX.

The greenPIX project was designed by Brooklyn based Simone Giostra & Partners Architects in collaboration with ARUP for the Xicui Entertainment Complex in Beijing and is the largest LED display in the world. The project is also the first building facade integrated PV system in China. The building is located in western Beijing close to a number of 2008 Olympic venues. The singular design brief given to Giostra was to ‘enliven the building’s opaque, boxlike presence and connect it to its environs’ all using only one facade.

Media displayed on the large format low-res screen can be presented in both film and still image formats, with the consideration that artists must consider and plan for the implications of jumbo size and low resolution. To account for this, the designers developed a special software package (windows) to allow potential artists to test their creations on a virtual facade before loading it into the media wall. The software shows the facade presentation in a rudimentary 3D cityscape mockup and makes it possible to view the wall from many angles and distances to test the resolution.

In one example of potential media presentations, artists created an infrared heat map generated solely by locating all the occupants of the building and showing their position in relation to one another. The resulting animation is a dynamic representation of real-time events and begins to address the designer’s vision of the wall as a way of linking the building and its occupants to the environs.

The entire facade display is roughly 24,000 squaure feet. Each of the 2,292 glass panels comprising the facade has a color changing LED fixture mounted behind it and is a ‘pixel’ in the large format low-res display. Integrated photovoltaic cells mean that the panels both emit and absorb energy in the form of LED and sun light, thus reinforcing Giostra’s vision of ‘technological self sufficiency.’

‘Seascape’, the concept of dynamically changing scene based on both time and vantage point, also played a large role in the design of the facade. Media is the active dynamic element at night. During the daytime however, when sun obscures the LED light, Giostra had to make the passive elements of the facade appear dynamic. He accomplished this by varying opacity and mounting angle (5°) of the glass panels as well as by carefully arranging the integrated PV cells to form a dynamic pattern. The result is a facade that appears to undulate with the rhythm of the environment day and night.

Interestingly, the entire system is a total of seven feet thick including glass panels, structure, power and data infrastructure, LED lighting fixtures and a maintenance access space.

Below is a video interview of designer Simone Giostra discussing the greenPIX project.

For more information please visit the greenPIX website or read ID Magazine’s article on Simone Giostra titled “A Gleam in the Eye.”

GCS Radiant Flooring is a modular, hydronic radiant floor system which is designed for easy installation, simplified maintenance and energy efficiency. Like most energy efficient radiant floor systems, GCS panels heat space using a network of plastic tubes circulating preheated water (or a glycol/water solution). Think of this system as a grid of pre-milled slots designed to hold the hot water tubes in place under the finished floor. What makes these panels unique is their manageable size, easy installation and energy efficiency.

GCS Radiant Inc. claims that installation can be done by as few as one person, with a recommendation of two. Each panel is a sandwich of concrete and a plastic substrate molded to receive the hydronic tubing. Units are small enough to be easily handled by installers and are fastened by only four screws. If there are any problems with the hydronic tubes the affected panels can easily be removed (unscrewed) to make repairs. This is not the case with hydronic systems poured into slabs, as the slabs must be cut to reach the tubing.

Panels are also designed to spread heat evenly within the substrate. The concrete mix in each unit is able to absorb and spread the heat effectively and creates more thermal lag in the space, leading to more even heating and reducing the number of cold areas on the floor where tubing does not occur. The accompanying images show thermal characteristics of the radiant floor units.

It is encouraging to see material manufacturers submit their products for this type of testing and evaluation. It appears as though GCS Radiant Inc. has allowed data about heat movement in concrete surfaces to affect the design of their units. The result is a modular radiant floor system with the benefits of both and accessible and a poured concrete slab radiant system.

For more information visit GCS Radiant Inc.

Process

Absorption chillers use the process of evaporation, instead of Charles’ Law (as in the case of compressor driven systems), to generate coolth. The process uses a heat source, a tubing and container system, three substances (ammonia, hydrogen gas, and water) and goes something like this (described below is a ’small ammonia’ refrigeration cycle – for reference):

• First – In the Evaporator, liquefied anhydrous (containing no water) ammonia enters a chamber filled with gaseous hydrogen. Hydrogen takes up space so the rest of the system stays pressurized, but per Dalton’s Law the ammonia acts as though the pressure was decreased, and begins to boil. As the ammonia boils it absorbs heat and produces the coolth required by the chiller.
• Second – The Absorber mixes water and the hydrogen/ammonia gases and the ammonia condenses into the water (hydrogen and water do not mix). Once the mixture reaches the bottom of the cascade of tubes the ammonia and water are thoroughly mixed and the hydrogen is free to circulate back to the evaporator .
• Third – The Generator separates the water and ammonia by using the heat source to boil out the ammonia! Ammonia gas/water bubbles are generated and a Separator removes the water bubble from the gas it contains.
• Fourth – A Condenser, or heat sink, removes excess heat from the system and brings the ammonia back down to room temperature.

Above is a reference diagram to help explain the process:

For more information please visit the original Wikipedia article.

Sustainability is a simple concept with a varied and challenging means of execution, and it is easy to falter, especially when faced with the myriad of devices, controls and systems designed to make buildings more sustainable. Searching for the latest, most sophisticated strategy for increasing a project’s sustainability does not translate into a sustainable building. The results of chasing technology can be increased budgets and memorable interviews, but in post occupancy building analysis designers may find that the added cost was suffered for only modest gain.

“Cover the basics first.” – Steve Lee, Sustainable Design Program Director, Carnegie Mellon University School of Architecture

Occupants, maintenance personnel and building owners (and thrilled bloggers of course) are the ones most affected by any disparity between predicted and realized benefits. With significant complexity comes greater chance for failure. So how can designers avoid chasing technology? How can technology be used appropriately as one tool in the toolbox of a sustainable designer?

The answer, I propose, is to divide design strategies into two categories: passive and active; and to prioritize the passive strategies as fundamental in the design process. Start any design process by considering building location, orientation, envelope and program. Link these passive basics together with a strong concept. Then layer increasingly complex active strategies onto this sturdy sustainable foundation. Several wonderful examples of this philosophy have been built and one shining example is the SIEEB building for the Tsinghua University in Beijing.

The Sino-Italian Energy Efficient Building (SIEEB) was designed by Italian Architect Mario Cucinella, in collaboration with Milan Polytechnic, the Ministry for Environment and Territory of the Republic of Italy, and the Ministry of Science and Technology of the People’s Republic of China. The project created a 20,000 sq. meter headquarters for an organization, the Sino-Italian Cooperation Program for Environmental Protection, dedicated to ‘education, training, and research with a focus on energy conservation and emissions reduction.’ The building is just over 40 meters tall, cost $32,000,000 and was completed in 2006.

Stated goals for the building were energy efficiency, low CO2 production, healthy indoor air, water recycling and reuse, resource savings in construction materials, minimization of environmental impact in construction and occupancy, intelligent control systems for occupants and maintenance, and durable materials.

It is important to note that an intensive integrated design process was adopted for the project. In fact the project was developed through a series of tests and computer simulations which helped define the optimal shape, orientation, envelope and systems appropriate for the building. These early conceptual building studies were allowed to influence the architects vision and clearly had a strong affect on the building shape and character.

Passive

The SIEEB is symmetrical (east-west) in plan. A thin building section created by adding a central courtyard minimizes the distance between an occupant and the exterior. Daylighting space becomes a much more viable strategy and dependence on artificial illumination can be reduced. The courtyard facades feature pivoting glazed louvers with a reflective coating that help regulate daylight and solar heat gain within the building. Multi-level terraces open to the south and expose the building to solar heat gain in the winter at shallow sun angles. The terraces also provide public space and area for vegetation. Shading these terraces are angled photovoltaic panels. East and west facades feature double glazing with integrated horizontal sunshades. This helps to mitigate the heat and light from the strong morning and evening sun. The north façade is opaque and insulated to prevent heat loss from the cold northern winds.

Location, orientation, envelope and program. The design team took a very complex design brief and boiled it, at least the concept, down to a few simple rules that might apply to almost any project. The design moves are passive because they deal with building fundamentals such as geometry, materiality, orientation, and program concepts and provide a base onto which more complex sustainable systems can be layered.

Active

The SIEEB is dynamic. Layered onto the passive aspects of the building are a set of very innovative, intelligent, controllable systems that help the building reach its high sustainability mandate. State of the art active solar photovoltaic elements are central to the building design. In total over 10,000 sq. meters of building integrated photovoltaics (BIPV) help to shade the structure and produce operating energy for the project. These panels not only provide power but also shade for the building.

Electric generators driven by gas generators supply additional energy required to meet demand not met by the BIPV system. Due to the efficiency of the gas generators, and avoidance of grid power with ‘line loss,’ the supplementary electricity generation system produces significantly less CO2 than a similar conventional Chinese building. Leveraged onto this system is a heat recovery system. This system heats space in winter, heats water year round and helps cool the building in summer using an absorption chiller. An efficient displacement air system provides conditioned and ventilation air while ceiling integrated radiant panels help control temperature. A night flush system is used during summer months to provide cooling.

Dynamic also means that the SIEEB can respond to occupancy, use and time of day through the extensive use of sensors and override switches. Room temperature, lighting, and ventilation air are directly controlled by occupancy, temperature, light, and CO2 sensors. These sensors direct building systems to turn on and off on a ‘need’ basis which saves considerable energy. Controllability also means that occupants can tailor their space to suit their comfort range which means that maintenance staff gets fewer complaint calls.

The SIEEB is not a success because of the attractive ‘active’ building systems. Active systems do make the project stand out, but none of them are feasible if it were not for the ‘passive’ strategies used. The team began with a clear building mandate for performance. Onto that they added an integrated design process and a clear architectural vision aided, possibly derived from, the knowledge gained by an aggressive testing and simulation process. Passive fundamentals were designed directly into the project. Then, and only at the end, could ‘active’ systems be integrated into the design. The result speaks for itself.

For more information please visit Mario Cucinella Architects project website or the original post at Inhabitat.

David Byrne, co-founder of the Talking Heads, has turned the New York Battery Maritime Building into a musical instrument. Sitting at a old pipe organ, any ‘musician’ is able to sonically explore the complexity of the building’s system without ever leaving the composers seat. A heavy sound may be for structure. A light sound could illustrate mechanical. A medium sound might describe plumbing. Byrne has opened the often obscure world of complex building systems to the user, and in so doing has found exposed harmony between disparate systems.

At the Battery Maritime Museum, music is produced mechanically. Parts of the building are hit, causing girders to vibrate. Other elements blow air through pipes, creating whistles. Bumps, rattles, clanks, chirps, zings, whirrs, buzzing, and crunches are all notes in the instrument. No traditional tones are used. Controlling the cacophony is an old pipe organ Byrne purchased at an antique store that allows musicians to play melodies on the keyboard in notes ranging from low to high.

Byrne says about the concept for the installation:

It is very old fashioned… If they’ve ever lined in an apartment with radiators, they’ll be familiar with noises that start usually at night or early in the morning”

Interestingly, Byrne has never played the instrument himself in public for fear that doing so may inhibit novices from trying their hand.

“People were not intimidated about playing it when they realized what it was doing and it wasn’t set up like a conventional keyboard… I think it makes people feel less inhibited, because it is really transparent [in] what it’s doing… you can see the machine.”

I propose that Byrne, through ‘Playing the Building’, is alluding to the essence of sustainability. His proof is that even a complex system can be understood if only harmonics and transparency can be applied to help sort the complexity in our minds. What is sustainability if not the physical, procedural and psychological rationalization of the complex systems of ecology? Is there a better way to accomplish sustainability than through the thorough integration of systems on all scales?

Fascinating to me is the way this installation illuminates the systems comprising the building. The complexity, layering and coordination present in all good buildings, but so often obscured by skins and finishes, is made transparent to the musician. Furthermore, each device connected to create sound, has been tuned to exploit the qualities of the particular element to which it is attached. A steel beam might get a heavy percussive device. A pipe may have an air blower. Yet another smaller pipe may receive a small tapping device to produce light sounds. Whatever the building system or element, Byrne responds with a device that is ‘tuned’ to create sound most inherent to the element.

We as designers must understand buildings in the same way David Byrne’s musicians are able to comprehend the complex system within their musical instrument. Harmony and transparency may well help us to bring about a more sustainable future. We need to fully comprehend the harmonies between building materials, systems and program in order to create smarter designs. We need to produce building systems that are more translucent to the occupant so they can comprehend at a glance the implications of their behavior and feel empowered to modify their actions.

So I say to all building designers out there. If we just listen to our building’s systems, we might finally understand how to play a symphony, a sustainable symphony.

For more information please visit the ‘Playing the Building’ website or an interview with Byrne about the project on NPR.

”to make as effective, perfect, or useful as possible“ -Definition ‘Optimize’

The National Aquatic Center in Beijing achieves sustainability through the optimization and integration of its structure, envelope, and building systems. In doing so it tells the story of how a little known problem of theoretical physics, Kelvin’s Conjecture, influenced the design of a prominent international building by leveraging advances in information sharing, computational modeling and materials science. Combination of these world ‘flattening’ innovations with architectural vision and pure science delivered a stunning and sustainable building. Furthermore, their integration describes a new paradigm in the building design process which is poised to revolutionize the practice of architecture. And sustainability, not obvious at first glance, permeates the design, materiality and final form of the Water Cube.

Interestingly, the project forced a blending of the disciplines and responsibilities of architects, engineers, contractors, materials developers and scientists. Each segmented discipline was asked to help solve issues related tangentially to their own domain. Integration was so rigorous in fact, that the building design necessitated the development of new advanced software for analyzing building behavior. The overall outcome was a integration of disciplines and mastery of technologies which is not always required on more traditional building projects.

Description

The 70,000 sq. meter National Aquatics Center, also known as the Water Cube, is being built for the 2008 Summer Olympics in Beijing, China at a cost of roughly $140 million dollars. Construction began in December of 2003 and was delayed past its 2006 deadline until January of 2008. It is located in the Olympic Green Precinct adjacent to Herzog and de Meuron’s Olympic Stadium. The center measures 170 meters long by 170 meters wide and is 31 meters tall. During the games it will hold over 17,000 spectators for the aquatics events.

Design Process

The project was conceived as part of a design competition won by the team of PTW Architects, Ove Arup Australasia, the China State Construction Engineering Corporation (CSCEC) and the Shenzhen Design Institute (CSCEC+Design). Interestingly, the brief, beyond just the programmatic requirements, included requirements for ‘extensive use of digital technology, energy-reduction, water savings, and use of new construction materials’. From the start, these few simple inclusions in the design brief insured that the winning ‘water cube’ would exceed expectations in terms of design and delivery. Tristram Carfrae, of ARUP engineering notes:

“Unusually, we at Arup began the competition process by outlining to the architects what we wanted to achieve technically, based on our previous experience with aquatic centres; bringing into play a whole gamut of engineering disciplines.

As swimming pools need to be heated for most of the year, we decided that the solution that solved most of the technical problems was an insulated greenhouse. Diffused natural light would enter through a main steel structure built within a cavity, to isolate it from both the corrosive pool-hall atmosphere and from the outside. Arup also reasoned that ETFE, a transparent form of Teflon, would be most efficient for such a greenhouse, removing the need for a secondary structure and providing better insulation than single glazing. The architectural planning team concurrently calculated that the entire square site would be needed to fit all the required facilities into the centre.”

The ARUP engineer adds that the design for the ‘water cube’ was, in part, a reaction to the unveiling of the adjacent ‘red birds’ nest.’ As a result, the submission, the ‘water cube’, was conceived as blue box of bubbles. What the design team did not know was that the concept of a box of bubbles would lead them on a journey through obscure scientific research; that a beautifully simple concept might not point to a straightforward technical solution.

How then should the team technically achieve their vision?

The team first set about rationalizing the design concept as a series of vertical cylinders. The cylinders would have circular ETFE panels at the top and bottom. The problems with this solution are easily apparent however. Cylinders do not fit well together and what should happen at the intersection of vertical and horizontal surfaces? How are these areas rationalized and does that rationalization lead to a feeling of random bubbles?

At this point the team had to ask “what sorts of shapes fill three dimensional space uniformly?” And what shape would give the impression of random bubbles?

In a precursor to the methodology used throughout the project, Tristram Carfrae notes that “(He) suspected nature would provide the answer, from living cells to mineral crystals.”

Kelvin’s Conjecture

“How can space be partitioned into cells of equal volume with the least area of surface between them.” – Lord Kelvin, Kelvin’s Conjecture, 1887

The design team found that they were not alone in asking this question. Theoretical physicists had been trying to solve Kelvin’s Conjecture for over one hundred years. Kelvin himself proposed that the solution was a 14-sided polyhedron with six square sides and eight hexagonal sides. Kelvin’s solution was considered most efficient for over a hundred years. That was until in 1998 when two physicists, Denis Weaire and Robert Phelan, using computer generated simulations of foam, found a more efficient solution. Their solution was in fact 0.3% more optimized. It is composed of two types of cell: an irregular pentagonal dodecahedron and a tetrakaidecahedron with 2 hexagons and 12 pentagons. Some with slightly curved surfaces. This solution is known as the Weaire-Phelan Structure. It was perfect.

The only remaining problem was that the solution when modeled appeared to orderly. The size and shape of the ‘bubbles’ was too regularized to be plausible as the solution to a ‘box of bubbles.’ The Weaire-Phelan structure delivered again because it was soon discovered that the structure, when sliced at arbitrary angles, appears ‘totally random and organic.’ The solution was therefore to conceive of a larger block of ‘bubbles’ rotate it and slice the ‘water cube’ geometry out.

It is important to note however that the façade is not entirely random. Out of a total of 4,000 bubbles there are only 22 variations of ETFE panel in the entire project (15 at vertical surfaces and 7 at horizontal).

New Software / BIM

Once the competition was won the team then had to set about actually engineering the structure. The Weaire-Phelan structure was optimized to use the minimal amount of surface area between elements. But that does not translate directly into an efficient structural system for a building. Somehow designers needed to figure out a way to test the structure and size the 22,000 steel tubes, 12,000 steel nodes, and 4,000 bubble panels that form the exterior cladding. The response by the ARUP team is astounding. They designed a new software package to optimize the structural system of the façade.

“[…]the structural optimization process sized all the steelwork members and their connections.”

The software then ported all this data into an accurate 3D CAD model that could be used to create construction drawings. The software package was developed enough so that in event of a major change in scope or design, it could re-engineer the entire structural system automatically in about a week. Instant building plans!

Fire, smoke and egress requirements were a second area where performance based simulation was extensively used. It was very important for the viability of the structure to prove that the individual steel members did not need to be covered in fire spray or fire resistant intumescent paint. In this case a modeling package called Fire Dynamic Simulation was used to provide data to Chinese authorities. Using the data engineers proved that the structure would resist fire for long enough to be safe as long as added measures such as sprinklers were used.

Critical too was the use of ETFE as the interior and exterior cladding. The design team had to prove that it would not be dangerous to clad the building in a plastic material. ETFE is, after all, a combustible material. The saving grace of ETFE is that it shrinks away from heat. This means that the building envelope is essentially self ventilating. It allows smoke to escape right through the building membrane giving occupants critical extra time to exit the building.

Building Performance

The ‘water cube’ is designed to be a greenhouse. Two layers, an exterior and interior, of ETFE create a double membrane barrier mediating the exterior and interior conditions. This arrangement has an effective ‘negative U-value’ because the building envelope is able to capture more heat energy in the form of solar radiation, than it looses through convection, conduction or radiation back out through the facade. Furthermore, the high thermal mass of both the pool water and the concrete structure around the pool ensure that heat remains in the building during the nightly cooling period. Designers predict that this strategy will help cut pool hall energy consumption by over 30%!

Overheating could be a problem however. The designers therefore selected a ‘frit’ patterning on various layers of the ETFE in order to reduce heat gain in the summer and maximize heat gain in the winter. A second strategy of ventilation within the exterior envelope, between exterior and interior layers of ETFE, keeps the envelope tempered year round.

Stratification and displacement are important concepts to the energy efficiency of the building. Engineers allow the air within the pool hall to stratify so that the entire volume does not have to be brought into comfort ranges. This in combination with a displacement conditioning system that brings tempered air directly to the user at the bottom of the volume reduces energy consumption by a factor of ten. Excess heat from the condenser units is also used to heat the pool water. In combination, these strategies significantly lowered the energy footprint of the building beyond what a typical aquatic center would require.

Conclusion

The ‘water cube’ is sustainable because of it’s optimization. Optimization of concept. Optimization of skin. Optimization of structure. Optimization of energy use. Optimization of fire control. Optimization in the water cube occurred at many scales and across many strategies, and they all worked in concert to deliver a building design that was more sustainable than any one part taken independently. We have seen how this optimization occurred.

The competition brief catalyzed an integration of ideas at the inception of the design process. The involvement of ARUP, and specifically their statement of the critical performance criteria for an aquatics center early on in the design process drove the direction of the project. In fact that early injection of a scientific method into the process allowed architects and engineers to benefit from one another’s experience and knowledge and left the door open to investigations outside the realm of pure ‘building’ sciences.

Asking the right fundamental questions, on the part of ARUP engineer Tristram Carfrae, made possible the uncovering of Kelvin’s Conjecture and the eventual optimization of the entire building structure. Advances in material science allowed the design team to select materials with appropriate properties for the project. With regard to smoke evacuation and heat gain, designers were able to customize ETFE to suit their exact specifications. In addition, simulation software helped optimize the structure, systems and operation of the building before any construction began. This gave the client the confidence to sign off on the design even with a very ambitious proposal.

The process was made possible by advances in simulation technology, material science, and information sharing that are just starting to affect the way our built environment is created.

The results are breathtaking.

For more information please review the following reference articles:

Ingenia Online – Box of Bubbles

Guardian Newspaper – Welcome to the WaterCube

Design Build Network – Water Cube

For a quick history lesson please take a look at the wikipedia.

Energy Recovery Ventilation (ERV) refers to the recapture of energy typically lost through the building ventilation process. Conditioned air that is routinely being exhausted from both residential and commercial buildings contains significant energy in the form of heat or coolth and humidity which is lost into the exterior environment. As part of a preconditioning process, ERV systems transfer the energy from the exhaust into the incoming air stream, which can also be described in terms of enthalpy. The use of ERV can have significant benefits both directly and indirectly in terms of energy efficiency, indoor air quality, and downsizing of the remaining HVAC equipment.

It is important to note the difference between Energy Recovery Ventilation (ERV) and Heat Recovery Ventilation (HRV). ERV exchanges both temperature and humidity between the exhaust and incoming air. HRV only exchanges thermal energy. The difference can also be stated as Total and Sensible or just Sensible energy exchange.

ERV systems are gaining popularity for a number of reasons. First, the technology and manufacturing processes are making the systems more affordable. Secondly, increased awareness of energy efficiency and sustainability both for environmental and economic reasons are causing more building operators to request such energy saving measures. Last and perhaps significant, increased ventilation to prevent Sick Building Syndrome (SBS) and promote healthy indoor environments results in a dramatic rise in energy consumption. Heavy ventilation or air changes requires the use of ERV technology, especially in the case of Passive Houses, high LEED certifications and most high performance buildings. In the United States ventilation standards are set by ASHRAE 62 which are used for both LEED and a general standard for high performance buildings. There is a growing body of data to suggest the health benefits of healthy indoor environments and updates to ASHRAE 62 are a recognition of that evolution.

An Opinion on ERV

ERV technology will likely develop further as awareness of occupant health, environmental sustainability, and energy cost grows. Right now we can recover up to 85% of the energy from the exhaust air, maybe in the future it will be possible to recapture even more. Costs will be reduced. The systems will be easier to integrate.

But to me the most exciting aspect of ERV technology is the idea that we can harvest latent, waste energy from our buildings, systems, occupants and environment. Renewable energy sources do roughly the same thing except they recover energy from the largest system of all, the planet itself. Wasting renewable energy supplies is unwarranted but probably inevitable. Entropy will occur in a system, but blatant waste of energy we have already generated elsewhere is shameful. Buildings use energy generated from coal fired plants, nuclear facilities, and other carbon and pollutant producing sources. This energy pollutes our environment when it is created. Costs real money. And therefore should not be thrown out into the environment. On a larger scale, projects like the Zollverein School and Hammarby Sjostad are have started to engage the idea that buildings can recover waste heat energy but the technology has not advanced far enough.

Who knows, maybe an adoption of ERV systems will cause a sea-change in the way people think about energy!

All photos by Mikkel Strange

The Danish Smart House Eco is an environmentally friendly housing system which can be optimized in a number of ways to meet the space needs of both individuals and families. Creators Eva Kristine Borup and Stefan Valbaek of Valbaek Borup Architects, designed the system to be flexible to the needs of the occupants with regard to building orientation, number of floors, number of rooms and materials. Especially interesting is that the house is certified by the Danish Ecolabel Agency! (for more info visit Ecolabel)

The architects note:

“You can design your house precisely as you wish… small or large, two or three floors, with either your family at the center or your friends. The house can even be customized for the local environment.”

Important considerations by the designers were:

• Carbon footprint of the house
• Safety, health, and durability of materials used
• Record low heating costs for operating the house

For more information visit the Valbaek Borup Architects website or the original article at ByggExpo.

(above) Exterior views are available to all rooms

(below) High quality mahogany window wall and exterior ceramic facade

The U.S. Federal Building in San Francisco is one of the General Services Administration’s (GSAs) most visible attempts at designing a high performance government building. The project is one of many started following the 1993 adoption of the “Design Excellence Program,” in which the federal government sought to “reach into the private sector to find top quality design talent for new GSA buildings.” It is also one of three projects being designed as a collaboration between the GSA and Los Angeles based architect Thom Mayne of Morphosis architecture. High performance features of the building include: natural ventilation for all office spaces, no air conditioning on the upper 13 floors, sensor controlled natural daylighting, shading devices, individual controls for occupants, energy efficient elevators and a socially sustainable program. The GSA claims that these measures account for the roughly 33% energy use reduction above even California’s strict Title 24!

“Our primary interest was to produce a performance-driven building that would fundamentally transform its urban surroundings, the nature of the workplace, and the experiences of the people who use it while making intelligent use of natural resources. For me, this project represents … an architecture that synthesizes its complex forces and realities into a coherent whole.”

- Thom Mayne

Socially Sustainable

One explicit goal for the GSA is to promote government buildings that improve their local communities. It is easily overlooked, but Mayne’s 600,000 sf Federal Building complex actually consists of several buildings. On the southern side is a large urban plaza/park available to the community. The park is flanked on the west by a low bar building filled with office space and additional services. Both the park and the low building elements are examples of ’sustainable community buildings’ that encourage interaction between federal employees and the local community.

The program of the Federal Building addresses this need in three specific ways. First, the cafe was placed outside of the main building to encourage employees to leave the building and local residents to stop by for food. Second, the building opens up a number of conference facilities in the evenings for community events. Lastly and maybe most significantly, the GSA decided to locate the child daycare on the exterior of the building and open it up to the community, allowing local families to use the child daycare if they choose. Each one of these moves is a significant gesture in terms of encouraging interaction between the community and the government. It is worth noting that project executive Maria Ciprazo points to “sustainability in the neighborhood” as the measure of a sustainable building.

Energy Efficiency / Building Systems / Integrated Design

Mayne describes efficiency as the primary driver of sustainability and in those terms it becomes the mission of the design team to produce a high performance building. He does of course believe strongly in the expanded definition of sustainability including social, economic, and environmental issues, but in this case he seems to be guided by a predilection for making the building as efficient as possible.

That said, in order to achieve 33% reduction in energy use over and above California’s Title 24, Mayne had to begin designing for efficiency from the start using a highly integrated design process. Project manager, Tim Christ describes the process Morphosis and the rest of the design team started in order to ‘make the building specific to the temperate climate of the site.’ “We looked at 50 years of weather data in order to optimize the basic design moves and tie them to the site,” says Christ. Siting, orientation and massing maximizes the amount of sunlight that can filter into the unusually narrow footprint so sunlight can penetrate deep into the building. Daylighting helps reduce the need for heat generating artificial light and cuts down on the energy required to light the space. In addition, a series of inexpensive sensors measures the amount of daylight entering the building and automatically dims the light up to 0% if possible.

Excess heat gain on the southern facade is dissipated by a perforated metal scrim that blocks 50% of the solar radiation before it strikes the building. The sculptural scrim also undulates over the rooftop to form a cap on the building and down to the plaza where it becomes a fractured shading element. The northern facade is covered by vertical glazed louvers designed to block out low sun angles in the morning and evenings.

In order to design the most efficient building possible designers also looked to how the glazing system might affect the size and operation of the HVAC system. It was identified quickly that natural ventilation for outdoor air was preferable but how could this be achieved in a conditioned building. It was at this point that Mayne asked a simple and profound question. “Can the air conditioning system be removed?” he said. The response he got was that it was ‘plausible.’

The result of that questioned assumption and ‘plausible’ answer is that the top 13 floors of the Federal Building do not have air conditioning. The roughly 7% of project cost not needed to air condition those floors was reallocated into the design of the facade. Project Manager Tim Christ describes the system as using a “nightflush.” The building relies on diurnal temperature shifts of roughly 20°F. Temperature sensors on the facade open the ventilation windows each evening and admit cooler outside air into the building. Heat energy stored in the building’s exposed concrete structure is removed by the cooler night air. Temperature sensors within the concrete monitor the internal temperature and signal the windows to close once there is sufficient coolth within the mass of the building. In concept, each morning the building has enough coolth stored within its structure to radiantly cool the spaces throughout the entire day.

The facade is also used to naturally ventilate the space and give individual control to the occupants. Interestingly, it is unusual to have an operable glazed panel on an office building because of building code issues, but Morphosis argued that they met a higher standard of life safety. Thus they were allowed to proceed with the designed operable windows. By giving each user the ability to ventilate their immediate space, Morphosis essentially promotes what is already a common standard in most European office buildings, individual control of systems.

Workspace Quality

Workspace quality was very important to the design team. In a reversal of common practice Mayne elected to place employees along the perimeter and managers on the interior. He argues that this increases interaction between management and staff and promotes engagement between colleagues. Another significant cultural change the architects promoted is the skip-stop express elevator system. These elevators are designed to have stops on every third floor. The result is a net savings in energy and the possibility that an employee might need to walk a flight of stairs up or down to get to their floor level. Additionally the design necessitates the creation of intermediate building lobbies to service the elevator stops. Building occupants have thus far reacted positively to the increased social interaction the ganged elevator lobbies provide.

Discussion

The overall sustainability of this building is an interesting debate topic. Judging by the energy saving technologies it appears to be very sustainable, certainly high performance. But if we look closer we may find that the excess use of stainless steel in unneeded areas along the facade and excess vertical glass on the north of the building usurp unjustified quantities of materials in a building. Would the sustainable approach not be to minimize the materiality of the project. It is certainly Mayne’s MO to adorn his buildings in a conflicted irresolute skin of excess material to illustrate the complexity of site and program conditions, but is that argument justified in a sustainable building. I have heard arguments going both ways on this subject.

For more information please visit the source articles at Arcspace, Treehugger, Architectural Record or at Wikipedia.

svgallery=SVGallery_SFFederalBuilding

30°C Coal Mine Water + Radiant Exterior Wall System + Structure = Active Thermal Insulation

The Zollverein School of Business Management and Design building is a model project for systems integration. It uses a sophisticated Active Thermal Insulation system consisting of preheated water circulating through the facade which allows for thin exterior structural walls perforated with randomly large openings. The effect of this system on the design of the building both spatially and formally are striking. Furthermore, in the process of creating the school, designers leveraged advanced technology, architectural vision, smart engineering, and free heat energy found on site to create a sleek form which endows even the project methodology with elegance. The Zollverein School is a testament to the benefits of integrated systems and integrated design.

The Zollverein project started in 2002 when Japanese design duo Kayuzo Sejima and Ryue Nishizawa of SANAA won a design competition to develop a building for the Zollverein School for Business Management and Design. The site, a recently master planned redevelopment of the Zollverein Mining Complex by Rem Koolhaas/OMA, is located near Essen, Germany (see the master plan). Interestingly there is such historical presence in the area that UNESCO awarded it status of World Heritage Site in 2001. It should also be noted that in 1986 when the heavy coal mine was shuttered , it was one of the largest and most technically advanced mines in the world. The significance of the site no doubt played an important role in the development of both the aesthetic vision and the technical solution of the project.

Design Concept

The initial concept for the project was a concrete cube 35m by 35m (~5,000 sq. meters) perforated by thousands of small apertures of different sizes. Program for the four story structure includes a presentation hall, an exhibition hall, a cafe, design studios, library, offices, and a roof garden. The interior spaces were designed to be expansive and largely column (structure) free.

“Our aim was to achieve transparency in the concrete structure.” -SANAA

Fundamental Design Challenge

The problem with the sheer number of apertures originally designed was threefold: 1) too costly to implement because of glazing 2) structurally challenging 3) the depth of the wall meant that the windows would be very deep. For these reasons SANAA began to look alternatives.

The first most obvious move was to reduce the number of openings and increase their respective size. This move reduced glazing costs and helped the structural design. The second strategy was to systematically reduce the weight of the floor plates within the building by using displacement air bladders. The strategy reduced overall floor plate weight upwards of 30%. The reduction of weight within the floors significantly reduced the amount of structure required inside the building volume.

The remaining challenge then was then how to deal with the thick exterior wall insulation required by German energy efficiency standards.

Integrated Solution

The solution was flowing right past the building. Hot (30° C) pit water was constantly being pumped out of the nearby mine shafts from depths of over 1,000 meters; removed continuously to prevent collapse of mine walls below. Unfortunately the hot water (energy) was not being used for anything. In fact, the water had been dumped continuously into the River Emscher for years.

Luckily the Zollverein School building was allowed to take advantage of the excess heat energy. Using a water to water (likely glycol filled to prevent freezing) heat exchanger, project engineers designed a system of radiant tubes that spreads the heat energy from the mine over the facade and floors of the building. The system significantly reduces the need for insulation on the exterior walls of the building. It also allows the walls to be only as thick as the structure itself. An added bonus is that the system can be used to pipe cool water through the building in the hot months of the summer thus cooling the building radiantly.

The results are striking. The solitary naked concrete cube is at home amongst its neighboring relics of industrial production. Randomly sized glazed openings scattered on the facade arranged according to spatial condition on the interior lend the exterior an abstract industrialized quality. Most striking to me however is Integrated Design process which produced the Active Thermal Insulation System.

Discussion

What SANAA has done with this design problem is establish a juxtaposition between architecture and engineering that asks both to accommodate fundamentally alien criteria. Transparency and concrete structure are generally not elements that work together. In this case however the architectural vision was based on finding a solution that allowed a heavy bearing material to be light and translucent.

I think the Zollverein School is a reminder that an informed sustainable design concept should take into account all the requirements of a building and site before setting the course of the project. The case of the Zollverein School is not unique, and is at the heart of a debate about how to design buildings. Namely, is a building a result of an integration of systems directed by an architectural vision? Or, is a building the result of a primary, elemental vision that supercedes all other requirements? The Zollverein School proves that both paradigms can produce significant works of architecture, but it still remains to be seen whether or not both methods in fact produce sustainable buildings.

Looking into the future, I would argue that truly successful designers must start seeding their building visions with an extensive knowledge base of history, engineering, sustainability, economics, and aesthetics. Then nurture the project from vision to building using an integrated design process which takes advantage of expertise outside the reach of architecture.

For more information please visit articles on the building at Arcspace, Detail Magazine or read a brief posting of the topic on Treehugger.

Many images presented here are the work of Thomas Mayer. Please visit his gallery for more photos of the Zollverein School building.

svgallery=SVGallery_Zollverein

The Smith House, located in Urbana Illinois, is an all electric house built to the German Passive House Building Standard. To achieve the passive standard, architect and owner, Katrin Klingenberg, created a clean, efficient and comfortable house design using many of the passive house design strategies used in German model buildings. She describes the house as a “simple shed-roofed house insulated on all six sides to at least R-56.”

It is worth noting that Klingenberg ‘tweaked’ the Passive House standards to meet the unique climate conditions of Illinios, but that doing so did not compromise the strict energy efficiency criteria required to meet certification. The measured performance of the house is in fact below the level set by the Passive House standard. “The program specifications were written for Germany,” she notes. “But the climate here in Illinois is way more severe.” In designing Smith House to meet the Passive Standard in Illinois, the architect used several sophisticated computer models to refine the details of her thermal envelope including consideration for solar heat gain, internal heat gain, occupancy patterns, and energy loss through the skin of the structure. Klingenberg notes, “The surface/volume ration has to be very good… you do not want to have a lot of nooks sticking out of your house… because you lose energy.”

The Smith House design contains all the typical elements of single family home but with modifications to meet the Passive House Standard.

Envelope Design

The building foundation is uses a concrete slab poured over a 14″ thick layer of expanded polystyrene insulation (EPS). To keep heat from entering the slab at the edges, Klingenberg uses a 10″ thick concrete-block frost wall with 6″ of EPS on the exterior. Above grade this EPS block wall is shielded by a slate finish.

Exterior walls of the house are constructed using 12″ “Trus Joist” I-joists (TJIs) filled with blown fiberglass insulation. The wall cavity is sealed using OSB on both the interior and exterior sides. The exterior layer of OSB is covered completely in a 2″ layer of EPS secured with strapping back through the TJIs. A result of this thick wall is that it overhangs the foundation by 4″ and naturally provides a shield for the slate finish below.

To reduce infiltration into the interior, Klingenberg placed no electrical boxes in the exterior envelope. Instead the electrical boxes are all mounted on the the floor. In addition, light switches needed on the exterior are not hard wired. In leiu of hard wired systems, the architect found wireless light controllers that can be installed in shallow surface-mounted boxes. These two strategies were very important in maintaining the integrity of the air barrier.

The roof of the house is a “shallow-pitched single south facing plane framed with 16″ TJI rafters and insulated with blown in fiberglass.” Standing-seam galvanized roofing is installed as the exterior finish because of its thermal mass and reflective properties. There is a vent channel located between the roofing material and the insulation to allow built up heat in the summer to escape.

190 SF of fixed and operable triple-pane, argon, low-e windows allow natural daylight into the home. Most of the glazing is located on the south facade of the building both to admit daylight and solar heat in the winter months. In order to facilitate heat gain on the south facade glazing was chosen for its high Solar Heat Gain Coefficient (SHGC) of 0.51. That was varied on the west facade to SHGC 0.31 to reduce the impact of the hot western sun in summer months. Overall the glazing is rated to U-factor 0.17, which is roughly double the insulation of even the most efficient typically used glazing panels.

Systems Design

The Smith House uses a typical $450 instantaneous domestic hot water heater by German manufacturer, Stiebel Eltron. Klingenberg chose to use a low-cost low-tech tech system because of the relatively long payback and high maintenance attributes of Solar Domestic Hot Water systems.

Co-Creator of the Passive House Standard Dr. Feist agrees with this decision in principle by saying:

“We don’t calculate payback times—not on houses and not on solar thermal systems,” says Feist. “Instead we look at the annual energy cost and at interest costs. We can calculate the cost per kilowatt-hour saved from adding insulation, and compare that to the cost of including a solar thermal system. Solar thermal is by far the highest cost of any of the features we are discussing at the moment.”

The conditioning and ventilation system is designed to be simple and efficient. First, Smith House uses a Heat Recovery Ventilator (HRV or ERV) chosen because of the sophisticated climate controls available on the unit. The ERV uses the control / monitoring system to choose (using a damper) whether air comes preconditioned from an earth tube (8″ diameter x 100′ long) or, when outdoor temperature allows, directly from the outside. On very hot days air is also taken in using the earth tube to pre-cool the air. The house has no air conditioning (cooling). Heat is provided by an electric resistance heater located in the ERV unit. It is worth mentioning however that in most months the house requires little or no additional heating. “Last January the electric bill totaled only $35 despite the fact that the month included two weeks of -10° cloudy weather.

Cost

Building costs were higher than what could be expected for a comparably sized traditional home. Klingenberg notes that the construction is essentially a traditional ballon frame but that the build quality is higher. She estimates a 10% increase in cost to build such a home once contractors and designers become accustomed to the Passive House building standards. Klingenberg does note however that such a premium would be covered in about 10 years when calculating energy savings. The Smith House itself was built for roughly $110 per SF.

Smith House Project Details:

For more information read the original article or visit the Katrin Klingenberg / E-co Lab website.

For more information on Passive House design please visit Greenline’s previous post on the Passive House Building Standard.

In 2006, the Waldsee BioHaus became the first building in the United States to be certified with the German Passive House Building Standard. The house, built at the German Concordia Language Village of Waldsee in Bemidji Minnesota, uses about 85% less energy than a house designed to meet the Minnesota Energy Code. For that reason, the project’s architect, Stephan Tanner, notes that “the building is probably one of the most energy efficient buildings ever built in the United States.” Interestingly however, this energy efficiency does not come by sacrificing the occupant’s quality of life. Instead, the house envelope provides very clean and livable, naturally daylit, thermally comfortable spaces throughout the building.

(above) Architect Stephan Tanner gives a general overview of the Waldsee BioHaus

For more information on what is required in a Passive House design please read Greenline’s previous post on The Passive House Building Standard.

Passive House Design = Integrated Design + Tools

Of course meeting such a strict set of performance requirements has its implications on the general design and construction of a building. To begin with, every aspect of project planning must use an integrated design strategy to help coordinate decisions between architects, engineers, builders and occupants. For the Waldsee BioHaus, Architect Stephan Tanner and his design firm INTEP were chosen because they are specialists in integrated design and planning. What this means is that there is close coordination between all parties involved in the building project. It also means that parties are open to advice and criticism of their portion of the building design by other consultants. Furthermore it implies that the designers are all willing to adapt their designs to meet the needs of the project as a whole. Using an integrated design process also ensures that system integrity is maintained throughout the project. This is crucial in buildings that are striving to meet the Passive House Building Standard.

The tools available to designers of Passive House buildings are well proven and effective. In the design of the Waldsee BioHaus centered on several critical design strategies. These include: Passive Solar Design, Superinsulation, Advanced Window Technology, Airtightness, Ventilation, Space Heating, Efficient Lighting and Electrical appliances. The effectiveness of each of these strategies is of course linked back to how well any one of them can be reintegrated into the whole design of the building. Integrated Design. Below are a series of videos in which the architect describes the house and its systems.

Conditioning Systems

The HVAC system for the building uses several interesting technologies. First it is important to note however, that the foundation of those technologies is the superinsulated and supersealed envelope. Mr. Tanner explains that “the building has an open equal to less than one inch square over its entire surface. This is an incredibly tight envelope which allows for almost no infiltration between inside and outside air. Onto this efficient envelope is layered a highly efficient and correctly sized (for the load) conditioning system. To insure good indoor air quality the building replaces 100% outside air (no air is recirculated through the system). In order to keep energy costs low and still bring in 100% outside air, the designers start with an Air-Earth exchanger. The exchanger takes outside air and passes it through two 8′ deep by 50 foot earth tubes. These tubes warm (or cool depending on the season) the air to match the temperature of the ground (~55° F year round). This preconditioned air is then brought into the building through a heat exchanger (sometimes called an Energy Recovery Ventilator or ERV). The ERV transfers 85% of the thermal energy from the outgoing conditioned air to the incoming air. The entire preconditioning system means that by the time the heating or cooling equipment touches the outdoor air, that there is less than a 10° temperature difference between desired room temp and incoming air temp. This results in a huge energy savings and significantly improves the indoor air quality. (For more information see the video below)

(above) Tanner describes the super efficient house conditioning systems

Glazing

The Walsdsee House glazing system is an integral part of several passive house strategies. In the winter time the glazing panels allow solar radiation to penetrate deep into the space for heating and daylight. This strategy of course defeats the purpose of the passive house in the summer months and so the designers placed an automated/manual shading device on the outside of the windows. These louvers block solar radiation before it even reaches the building so they are not forced to deal with it on the interior of the space. One innovation is that the louvers can be rotated independently on the top and bottom of the window. The shades can therefore block the hot summer sun but still be rotated at the top to allow natural daylighting of the interior space.

The windows themselves are Passive House certified. The architect notes that they are rated to R-8 value and have several layers of seals and barriers to prevent infiltration and thermal bridging. (For more information see the video below)

(above) Tanner shows off the fascinatingly efficient daylighting / glazing systems

Solar Domestic Hot Water (SDHW)

Hot water and indoor heating are aided by the use of a roof mounted SDHW system. The panels absorb solar radiation and store the heat energy in a large super insulated storage tank located in the basement of the building. The tank can hold the heated water for extended periods of time and if excess heat is generated will automatically shed the energy through a heat exchanger outside (heat energy is also supplied by a air to water heat exchanger during instances where not enough solar radiation is available). The stored energy can be used for both domestic hot water (showers, appliances, etc) and to heat the house using the in-floor radiant floor system. (for more information see the video below)

(above) Here an engineer highlights the Solar Domestic Hot Water (SDHW) system

Quality of Life and the Future of Housing

In the closing video architect Stephan Tanner shares his personal (and mine for that matter) philosophy about buildings in the future. He describes that all of the technologies used in this building are available commercially and that their availability is being driven more and more by small innovative companies. Mr. Tanner then goes on to express his feeling that conservation is the only strategy currently working to solve the problems of our environment.

(above) A closing interview with Architect Stephan Tanner about the relevance of the BioHaus

svgallery=SVGallery_Waldsee

For more information on the Waldsee BioHaus please visit the project blogsite, the project construction blogsite, or Architect Stephen Tanner’s blogsite.

For more information on Passive House design please visit Greenline’s previous post on the Passive House Building Standard.

(above) The original Passive Houses in Darmstadt

The Passive House (Passiv Haus) standard is an ultra-low energy building design system which uses extremely efficient building envelopes to significantly drive down energy consumption in structures. The standard is completely voluntary but does have an extremely rigorous set of requirements that must be met in order to be classified as a Passive House. To date only around 6,000 buildings of all varieties including houses, offices, schools, kindergartens, and supermarkets have been certified. Of the total number of buildings, the majority are however houses.

The Passive House standard was conceived during a series of conversations between staff at the University of Lund, Sweden, and the German Institute for Housing and the Environment. Their initial ideas were flushed out in research papers and then proof of concept housing models were built at the University of Darmstadt, Germany, in 1990. These first buildings were a group of four row homes that proved to be 90% more energy efficient than comparable housing using traditional building methods. The standard is now being supported by the EU sponsored CEPHEUS program and has been adapted for use in several other countries throughout Europe and even the United States. (The American examples include the Smith House and the Waldsee BioHaus)

To be certified a building must meet a strict set of standards. These include:

1. The building must not use more than 15 kWh/m² per year (4746 btu/ft²) in heating energy.
2. With the building de-pressurized to 50 Pa (N/m²) below atmospheric pressure by a blower door, the building must not leak more air than 0.6 times the house volume per hour.
3. Total primary energy consumption must not be more than 120 kWh/m² per year
4. The specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m²

(The guidelines are flexible to a point depending on regional and climatic variation)

(above) The above thermal image shows heat loss from a Passive House (right) compared to a traditional house (left)

The comparisons between typical building codes and the Passive House standard are quite dramatic. For instance, in the United States, a house built to the Passive House standard results in a building that requires space heating energy of 1 BTU per ft² per heating degree day, compared to anywhere form 5 to 15 BTUs over the same period for a house built to meet the 2003 Model Energy Efficiency Code. This translates to between a 70 to 90% reduction in energy consumption for space heating and cooling. One Passive House home built in Waldsee Minnesota (at the Concordia Language Village) uses 85% less energy than a typical house its size.

Design and construction of these houses naturally follows a much more rigorous methodology than that used in traditional buildings (I would like to note however that as with most things, familiarity breeds efficiency and I would assume the same is true for new building methodologies). It is also worth mentioning that Passive Houses are documented to be no more costly than traditional houses of the same size. Designers are provided a “Passive House Planning Package” and use specially designed computer simulation software to predict the behavior of the building. Some of the design and construction strategies used in these houses are:

1. Passive Solar Design – leverage the sun’s energy by strategically lighting or shading the interior space
2. Superinsulation – high R-values for walls, floors and ceilings that are thermally broken whenever possible
3. Advanced Window Technology – usually employing triple glazed argon filled double low-e units with super insulated and thermally broken frames
4. Airtightness – minimize the amount of heat or coolth that escapes the envelope
5. Ventilation – including heat recovery ventilator systems and earth warming tubes
6. Space Heating – minimizes the size of heating components and maximizes internal heat gain from other heat sources in the building
7. Efficient lighting and electrical appliances

A word from Greenline – I applaud this building standard. It is amazing to see the reduction of energy consumption be so large just by employing essentially passive strategies. I know there are issues with the system such as mold prevention, indoor air quality, and natural lighting reduction, but the gains in efficiency make exploration of these strategies imperative. Greenline posted months ago about buildings in the United States using about 40% of all energy. Imagine that again if all our buildings suddenly became between 70% and 90% more energy efficient. And I do believe that is an achievable goal even given aesthetic, comfort, economic and policy constraints. It simply must be the case if we as a species are ever going to reduce our impact on the planet and keep our standard of living as high as I would personally like.

Stay tuned for more posts on Passive Houses!

For more information on the Passive House standard please visit: The Passive House Institute, The Waldsee BioHaus, E-co Lab Passive House Projects, and Wikipedia.

The two US Passive Houses are posted on Greenline as Smith House: A Passive House in Illinois and Waldsee BioHaus: First Certified Passive House in the US.