The finalist concept of the Metals in Construction 2020 Design Challenge focuses on reducing effort and resources on building refurbishment whilst still enhancing the façade performance of 63 Madison Avenue in New York – an archetype for US office buildings struggling with high energy demand and low user comfort. For this purpose “Active and Adaptive” carries the concept of ACT Facade forward which is already known to IGS readers from 2016’s Festo AutomationCenter project report.
Goal of the Metals in Construction Design Challenge was to develop visions for transforming the facade of one of Manhattan’s 60-year-old buildings to reduce carbon emissions and address the city’s Green New Deal – also presenting concepts as role model for broader application.
1. Focusing on what is necessary
Following the basics of a circular economy the Active and Adaptive concept aims for reducing construction and demolishing efforts to a reasonable minimum while at the same time increasing overall building performance and therefore extending the buildings life-span.
Regarding the geometry of the building, its surrounding and the plan layout 63 Madison Avenue reaches its potential in terms of space usage. Hence these particular criteria limit the potential in any changes or improvements of the building. Considering the building structure not yet reached its end-of-life an extensive refurbishment that cannot achieve its maximum potential appears inappropriate. Following Frank Duffy’s Shearing Layers of Change (see Figure 2), for 63 Madison Avenue counting 58 years a partial refurbishment that focuses on the energy performance would be the suitable choice in economical and sustainable aspects while remaining current building structure and façade. Hypothetically in 20+ years the service life of the all-over building structure and envelope will have ended. At this point it would be more suitable to fully refurbish or reconstruct the building with latest state of the art technology also utilizing the saved efforts beforehand.
Basis for this concept is the operating principle of the ACT Facade where used room air is sucked through a cavity in between exterior glass layer and an interior sun-shading layer of the façade to extract heat from solar radiation and creating a buffer zone. To enable a simple and cost-effective solution for 63 Madison Avenue and other office buildings solely a specially designed and operated three-part interior venetian blind will be added. With the activation of this inner layer the energy performance of the building by reducing heating and cooling loads and providing sufficient daylight can be improved substantially.
2. ACT Facade
The Active Cavity Transition (ACT) Facade is a combination of an external glazing with an internal adaptive layer such as a screen (see Figure 3) which acts as an adequate sunshading against sunlight and glare, which provides adequate conditions for creating a buffering cavity between these two layers, controls heat gains and allows views out.
Solar radiation typically causing overheating of the interior space is captured within the cavity between screen and glazing. The solar energy is absorbed on the surface of the screen and emitted in form of long-wave heat. Additionally, as in an exhaust air façade, the used air from the office space is sucked through this cavity by the central HVAC system. Therefore the air is only heated up in the cavity and together with its natural upflow it is sucked out from the top vents (see Figure 4). With this unwanted heating up of the indoor space is prevented. In addition the surface of the screen facing the interior has a low emissivity because of its low mass which could even be enhanced by a low-e coating and is cooled by air flow creating lower radiation temperatures to the inside of the building. For this reason, energy consumption is reduced as well by less cooling demand and improved user comfort.
Since the screen and exhaust air system can be operated individually, ACT Facade creates a variable g-value (SHGC) according to position of screen and operation of the ventilation system. An optimized operation of the ACT Facade is likely to be controlled by building automation system, nevertheless, it is possible to overwrite manually by the user. Due to the screen installation at the inner side of glazing, the system can be operated regardless of weather conditions like wind and is also less exposed to pollution or damage as other external shading devices.
3. Operation mode of Active and Adaptive concept
The refurbishment concept for 63 Madison Avenue aims to improve energy performance and user comfort of the building with little efforts. Thus the operation modes of Active and Adaptive dynamically influence the SHGC (g-value), the U-value as well improve daylight usage by controlled transmission and reflection. The novel interpretation of the ACT Facade using a venetian-blind instead of a textile screen generates therefore several operation scenarios
The lamellas of the blind are perforated to enable ventilation for exhaustion and view from the office space while at the same time securing sufficient glare control and temperature buffering within the cavity. Additionally the lamellas are coated differently on both sides: silver for high reflection of sunlight and for redirecting natural light at the top part of the blind and black for better view through the blind from inside and in winter for better heat absorption preventing major heat loss.
The adaptability of the venetian blind allows different façade performance / functions which handle different situations – summer, winter, sunny, cloudy, different in temperature and present of users (see Figure 5).
Thus the concept actively and adaptively improves the façade and building performancewhile causing minimal impact in the building structure and usage.
The system is designed as a separated add-on component, which could fit into any type of curtain wall and be adjusted to different façade and building layouts as long as the cavity between glass and venetian blind can be created and exhaust air systems connected to it. This cavity is used as a buffering zone for temperature regulation and protection throughout the year. For this the basis of the project is the individual operation and layout of the venetian blind in combination with the HVAC system.
Its simplicity and low technological demand makes the system easy, inexpensive, and quick in construction. The refurbishment can be done partially, which does not interfere with other areas that are still in use. Moreover the construction only requires access from interior, which reduces complication in the construction especially for a high-rise building.
4. ACT Facade – built and in planning
The principle of ACT Facade is not solely a conceptual approach but has been proven within several buildings already in operation and in planning as well as through research. The first ACT Facade has been realized at the Festo AutomationCenter in Esslingen, Germany (see Figure 6). A 67 m high-rise meeting the architectural intent of fully glazed high-rise and the companies’ thrive for innovation and energy efficiency. This first ACT Facade is in operation since 2015. The façade performance was verified not only by the user but also ongoing monitoring. This effectiveness and efficiency is also underlined by DGNB (German Sustainable Building Council) platinum certificate for the Festo AutomationCenter.
ACT Facade has been implemented successfully for retrofitting as well for EuroTower (see Figure 7) former European Central Bank Headquarter in Frankfurt, Germany. Only the interior shading system had to be exchanged and the air exhaust ducts were extended to reach an upto-date façade system as ACT Facade.
Besides these built examples further construction projects featuring the ACT Facade in Germany and worldwide are under planning. As for example the Ardex Tower with inclined façade units and two-layered screen system enabling different transmission and view properties (Figure 8), and the Continental Headquarter as the first low-rise building with an ACT Facade, due to more consistent façade design and lower operation and maintenance costs compared to an external sun-shading (Figure 9).
5. ACT Facade testing results
For the Festo AutomationCenter as well as Continental Headquarter further qualification of the ACT Facade by verified testing at the Fraunhofer Research Institute on Building Physics have been conducted. These measurements not only led to optimized solutions and confirmation of its façade performance but also have been used to finetune simulation models for further application. Showcasing that ACT Facade not only is able to reduce the g-value (SHGC) by 50 % but also cooling load for the interior by 25 % compared to non-ventilated standard systems.
In addition to project-based testing various general ACT Facade built-ups have been investigated at the Fraunhofer IBP. Inter alia also a venetian blind system as proposed for the Active and Adaptive concepts has been measured and been proven to be as feasible as a textile screen system. As shown in Figure 10 perforated lamellas have been used to enable an operation mode for suction of exhaust air from interior office space into the façade cavity. Air, surface and exhaust temperatures as well as air flow show comparable results as for the already realized textile screen based ACT Facade solution. This confirms the developed refurbishment concept of Active and Adaptive.
6. ACT Facade vision and potential
With new construction projects and architectural façade design intents new demands on the ACT Facade arise. However within this further developments on operation, materiality and components a compromise between view, glare, daylight autonomy and solar heat gain has to be found to improve user comfort as well as energy efficiency.
Therefore different variations for the screen layer seem possible for the ACT Facade as well as relevant to gain wider acceptance of the system by architects and clients through design and component flexibility. These include screens of various colors and openness factors, with ZIP or rope guidance, as venetian blinds as proposed for the Active and Adaptive concept but also as vertically relocatable curtains (see Figure 11).
For future applications of ACT Facade the combination with further technologies is envisioned (see Figure 12). Such as newly developed textiles for the screen including colored low-e coating, integrated PV and / or OPV, adaptive textiles through smart material integration etc. Moreover the whole façade unit can be enriched by using special energy harvesting technology such as translucent amorphous photovoltaic or PV integrated in the spacer within the exterior glazing – also enabling self-sufficient decentralized ACT Facade units. But ACT Facade itself is already equivalent to a solar thermal air collector, too. This thermal energy can then be used within the HVAC system for heat recovery, lowtemperature heating, preheating for domestic hot water, for de-humidification or even for solar-cooling through adsorption cooling.
Undertaken measuring and simulation plus realized and operating buildings show that the Active Cavity Transition (ACT) Facade is capable of creating high values of comfort and energy efficiency, meeting the demand of future building envelopes. In addition, the system is cost-efficient in investment on one hand due to the usage of state-of-the-art components, therefore also executable by various façade contractors. And in operation on the other hand due to energy and operation efficiency but also due to gain of maximized rentable area compared to e.g. Double-Skin-Facades.
Priedemann Facade Experts together with various partners inter alias WAREMA Renkhoff, Schüco and Transsolar conduct further research to evaluate these solutions and optimize the ACT Facade approach. Verifying simulation models accordingly, creating a higher flexibility of the system and its components and enable possible combinations of the system with other technologies.
Concluding within the ACT Facade concept lies a wide variety for broad application not only in new construction but also in refurbishment (see Figure 13) as it has also been awarded by the Metals in Construction Jury.
This article was originally published in IGS Magazines Summer 2020 USA Special Edition: Read the full Magazine here for more thought-leadership from those spearheading the industry
Author: Paul-Rouven Denz, Head of R&D | Priedemann Facade Experts
Paul studied architecture and urban planning at the University of Stuttgart and the E.T.S.A. Madrid with a focus on “resource-efficient construction“ and “building construction”. Mr. Denz has gained a wide range of experience during showcase building and research projects on sustainability in Germany and abroad. At Priedemann Facade-Lab, the competence centre of Priedemann Facade Experts group, Mr. Denz focuses as Head of R&D on research on new façade technologies, materials, systems and planning processes Since 2017 Paul-Rouven Denz is also a PhD guest researcher at TU Delft, Faculty of Architecture and the Built Environment, investigating Smart Textile Skin solutions for material and energy efficient building envelopes.