Building Science Forum©
By Brian Burton
Adaptive Building Enclosures + Systems
Virtually every component contained within modern building enclosures, including fenestration elements, is being revisited by manufacturers, designers and owners in on-going efforts to reduce operating costs, increase energy efficiency and improve the level of occupant comfort.
These efforts have been intensified over recent years partly as a result of the rapid increase in energy costs and the gradual recognition that the annual solar energy received on the building envelope surfaces is very close to being equal to the energy needed to operate the building. (This is true in all 4 Canadian climate zones.)
In theory at least, with improved techniques and technologies used to “capture” and then utilize this energy, we should be able to design buildings that are self-sufficient when it comes to energy.
As a result a great deal of attention has been focused on what are commonly referred to as “adaptive” or responsive building envelope systems.
These adaptive systems have the potential make it possible to effectively utilize more of this available energy for heating, ventilation, cooling, lighting and electricity supply.
One example of such an adaptive building envelope is a double façade* which incorporates natural ventilation systems. (*A curtainwall construction comprising an outer skin of glass and an inner wall constructed as a curtainwall that together with the outer skin provide a full function wall.)
An initial heat-insulated façade made up of folding wood and glass doors envelopes the space. In front of this a frameless, floor-to-ceiling slide-and-turn system is used as a non insulated glass layer. Both façades can be opened independently to varying degrees and may even be folded back fully, thus allowing staff to individually determine their preferred ambient room temperature.
Prototypes of adaptive façade systems have been developed to act as modular systems that combine six primary principals applied in various combinations:
- Decentralization of ventilation systems.
- Incorporation of flush integrated opening elements.
- Automated daylighting control systems.
- High-performance UV protection*.
(*Currently there are 3 technologies that make this light control possible: liquid crystal (LC), electrochromic (EC) and suspended particle device (SPD). These smart glass technologies enable control of the light that is transmitted into the building from 100% transmittance down to zero. This has a direct bearing on the temperature and heat build up inside the built environment and consequently on heating and cooling bills.)
- Solar energy production using modern thin-film technology.
- Modular/moveable interior insulated panels to minimize heat loss or gain.
These systems are moving away from the “centrally controlled” HVAC systems we have been accustomed to installing in the past to create systems that is more localised.
Instead of controlling heat loss and/or gain by moving warm air around the interior of the building using a central system, which is not really that efficient, the concept involves creating a system where at least some of these functions work together to adapt locally to exterior and interior environmental conditions.
The concept actually involves giving each area of the building what amounts to its own independent HVAC system (instead of a “one size fits all” approach).
The idea does however present a challenge not only because of the complexities involved but also because of the need to consider and balance moisture transport and movement within the system which is considered one of primary concerns in the industry.
If these types of systems can be effectively introduced and proven they could offer designers more flexibility and have considerable potential when it comes to reducing energy costs and improving building performance.
We’re not at the point yet where we can call these systems “intelligent” primarily because they don’t have the ability to learn from past experience. However we are moving quickly in that direction and I won’t be surprised in the least it some agency like the National Research Council comes up with a computerized mock-up that would qualify as “intelligent”
We also know that improving comfort levels and effectively controlling daylighting are important factors that affect occupant productivity in commercial buildings. Typically the financial impact regarding improved productivity is underestimated. In fact a 1% improvement can offset a company’s entire energy costs.
Effective use of daylighting and automated lighting controls improve energy use and employee comfort.
Another fact we have learned from experience in the field is that occupant’s usually insist on some form of “override” for daylighting controls and the number one complaint regarding these systems involves the inability to modify daylighting controls to meet specific needs.
Challenges
At the same time when it comes to assessing adaptive façades we still need to be able to reliably predict thermal and optical performance of components and systems.
We also have to consider the impact of increased cooling loads and cooling energy use for larger buildings and the potential for increased visual discomfort from sun penetration for people working at computer systems in daylighted offices.
It is very likely we will continue to see innovations of this nature as building professionals continue their efforts to focus on sustainability.
Brian Burton is the author of Fenestration Forum © and a member of the CSA’s Fenestration Installation Technician Certification Program Committee and NRC’s Standing Committee Task Group for Energy Efficiency in Buildings. Brian is an R & D Specialist for exp. and can be reached at brian.burton@exp.com or visit www.exp.com (*the new identity of Trow Associates Inc.)
Tags: adaptive building enclosure, commercial building energy efficiency, Commercial HVAC, intelligent lighting solutions
