Why natural airconditioning?

 

There are several arguments for replacing traditional air conditioning with natural air conditioning:

The human side

Air conditioning in buildings delivers room temperatures within the comfort zones during every season but is, nevertheless, only moderately valued by many people. We must not close our eyes to some inconveniences that this technique entails:

• In order to increase the capacity of the system as much as possible, the air is often so extremely cooled, 14⁰C or even lower, that it is not always possible to prevent draught at the workplace under all circumstances.

• The silencers especially attenuate the high frequencies but leave the low frequencies mainly untouched. For many people, this is very annoying.

• When passing through contaminated air filters, the air quality deteriorates. Additionally, rotary heat exchangers not only transfer energy but also air pollution. This is often not noticed directly, but it is not conducive to the quality of the air in the indoor environment.

• The infamous Sick Building Syndrome is more common in air conditioned buildings than in buildings with natural ventilation.

The technical-economic side

Traditional mechanical air conditioning has several technical and economic disadvantages:

• It is a complex technique that requires the extensive craftsmanship of designers and installers and is in contrast with the KISS principle.

• The often complicated control system requires significant maintenance management and is often not understood by users; therefore, the inherent maintenance often creates problems.

• The investment and maintenance costs are high.

• Space requirements are substantial for the equipment, and air ducts usually require an increased ceiling height.

• Integration of the HVAC system in the architectural/engineering design is often a cumbersome task for the architect and engineer.

• The mechanical air transport through the air handling unit and duct systems employ substantial electrical energy.

Energy aspects

Energy conservation in the building environment is an important task for the building construction industry. The formal objective within the EU, indicated in the EPBD[1] Recast (Directive 2010/31/EU) (EP and EC 2010) is:

“As of 31 December, 2020, new buildings in the EU will be required to consume “nearly zero” energy .  A “nearly zero-energy building” is defined as a building that has a very high energy performance, as determined in accordance with Annex 1. The nearly zero, or very low, amount of energy required should be almost exclusively produced from renewable sources such as energy from renewable sources produced on site or nearby “.

The energy referred to is the building-related energy consumption about which, in the Netherlands, a similar objective was formulated between the main actors in building industry in the so-called Spring Agreement (2008). In a European context, it is the “20-20-20” appointment which indicates that, in 2020, 20% of energy use in the building environment will be sustainably generated.

In the European Union, energy use is regulated by the Energy Performance of Buildings Directive. The Netherlands developed the Energy Performance Standard (EPN) whereby the energy performance of a building or dwelling is predicted by the outcome of an EPN calculation. The measurement of energy efficiency, the Energy Performance Coefficient (EPC), has been an instrument of the Dutch climate policy since 1995.

Comments on the Energy Performance Standards  

Limits for the EPC in a building have been periodically tightened. For new commercial buildings, including offices, EPC limits differ per building function. Anno 2012 is a requirement for office functions of 1.1 EPC. The requirement is set at the functional level, thereby allowing the designer maximum freedom in determining how to ensure that the required energy limits will be met. In addition, the requirement provides an incentive for the integrated design of the shell and building services and the design of energy efficient building concepts.

With this basic principal, however attractive to encourage integrated design, some critical questions and comments can also be stated. For example:

• Building services have only one overall life cycle of 15-20 years and are basically more vulnerable and more expensive to maintain than more robust structural facilities. Is it justifiable to place both categories on an equal footing based on the perspective of sustainability?
• In order to achieve the required EPC value, it is often easier and less expensive to employ less durable building services whereby more sustainable structural facilities will be omitted.
• Focusing on building services has, over the course of development, resulted in increasingly complex and maintenance-sensitive HVAC systems. Such systems often do not deliver the healthy indoor climate that may be expected, and a simple and intuitively understandable operation is hampered by the complexity.
• The energy expended to produce the equipment, the so-called embedded energy, is not valued in the EPC model.
• Innovative developments, such as those described below in the Earth, Wind & Fire concept, fall entirely outside the standardized calculation methods. Complicated and costly procedures to obtain equivalence certificates are then necessary.
•  Research shows that there is no statistically significant correlation between the predicted and the subsequently measured energy performance of buildings in the use phase.

Problem definition

It is unlikely that the desired “nearly zero-energy buildings” can be achieved by a further reduction of the EPC requirement with the application of improved construction and installation techniques. Constructional and physical building possibilities to reduce energy consumption are becoming exhausted. Improvements in building services are certainly possible but will be characterized by a decreasing value and also constitute a potential threat to the robustness of HVAC services and the cost effectiveness of the investment required.

Worrying scenarios in lowering the EPC requirement have further potential to reduce energy consumption in buildings by:
(1) reduction of the ventilation flows, threatening the deterioration of indoor air quality, and inherently contributing to a greater health risk in the workplace;

(2) avoidance of air conditioning  by application of natural ventilation only resulting in  deterioration of the thermal comfort in the workplace during the summer and inherently lower productivity of office staff;
(3) achieving the desired energy performance by utilizing cheaper, but also less durable, building services facilities instead of more expensive and more durable structural facilities.

These scenarios are also not in accordance with the Energy Performance of Buildings Directive, which also requires that:
“…requirements shall take into account not just the energy performance but also general indoor climate conditions, in order to avoid possible negative effects such as inadequate ventilation…

… measures should take into account  climatic and local conditions as well as indoor climate environment and cost effectiveness”.

Challenges for the construction industry

Energy conservation in the built environment is not the only challenge facing the construction industry as the HVAC sector especially stands out.

• The energy expenditure must be drastically reduced or renewably generated.
• However, this should not detract from the quality of the indoor environment.
• Finally, the measures must be cost effective as well.

Energy conservation in the building environment has primarily been the domain of building physics and HVAC technology. Both have, in recent decades, contributed excellent performance by providing a healthier, more comfortable, more productive, and safer indoor environment at a significantly lower energy use than before. Though the industry has revelled throughout the development of energy-efficient technologies for heat and cold generation, heat recovery, and energy-efficient HVAC systems, the end of this development appears to be in sight. A declining value in these sectors may be observed.

 “Research into building energy efficiency over the last decade has focused on efficiency improvements of specific building elements, like the building envelope, including its walls, roofs and fenestration components (windows, day lighting, ventilation, etc.) and building equipment such as heating, ventilation, air handling, cooling equipment and lighting. Significant improvements have been made, and whilst most building elements still offer some opportunities for efficiency improvements, the greatest future potential lies with technologies that promote the integration of active building elements and communication among building services.”

Challenges for architect and climate engineer

The integration of active building elements and building services, as propagated by ECBCS, lies within the domain of building physics and climate technology. The architect, the discipline that has the greatest impact on the built environment, still remains largely aloof. By directly involving the architect with his significant creativity and influence on the building process in the issues of energy and the indoor environment, new possibilities are, in principle, opened up on the basis of a truly integrated design. Giving architecture and architectural elements a place within the overall package of HVAC services in a building also complies with the primary objective of the study: reducing the distance of understanding between the architect and the HVAC engineer.

The innovative idea behind the research for Earth, Wind & Fire is the exploitation of environmental  energy from wind and the sun for the climate control of buildings. The central question is whether it is possible to design a building as a “CLIMATE MACHINE” activated by this environmental energy in combination with gravity.

In such a building, architecture, building mass, constructions and building services would jointly and interactively respond to the outside climate, thereby creating “NATURAL AIR CONDITIONING“. The air conditioning in this building is, in principle, created by nature and is much less dependent on technical installations.

According to the objective within the EU, this building would basically employ nearly zero energy and the residual energy use must be generated by the sun and wind.

Paradigm change

Against this background, a completely different way of thinking and design methodology is required for the design of the building whereby zero energy buildings can be realized in the short term while avoiding negative effects such as insufficient ventilation and uncomfortable indoor climate conditions. 

The direct deployment of natural elements for regulating the indoor climate takes the architect back to his basic profession of integrated designer, a role that he has always played in the past. He can practice his profession at a higher level by being the designer of the building as well as playing an important role as technical and artistic co-designer of the climate systems. “Back to the Future”.

For the HVAC engineer, comparable to the structural engineer,  it is a challenge to operate at a higher level of profession while significantly integrating with architecture.  However, by doing so, architect and engineer become capable of creating an overall design that incorporates indoor climate and energy facilities. Climate Technology also becomes architecture and vice versa. On the road to zero energy buildings, this appears an important and, perhaps, a necessary step.

The research for Earth, Wind & Fire is a quest for the necessary paradigm change in the building industry.  “Architecture and Climate technology working together symbiotically”.

Barriers

For centuries, it was necessary for the architect to take the local climate in the environment of buildings into consideration.  It was the task of the building shell to protect against heat, cold and sun radiation and, on the other hand, to make use of these for natural climate control. The shape of a building and the construction of the outer wall as an interface between the outer and inner environment was an important and dominant factor in the expression of the architect. Integrated designing in optima forma. We have seen this trend of integral design returning over the last decade in the development of the so-called climate-active components in bio-climatic architecture.  Such building and building elements respond to outside climate conditions through the change of physical properties for the improvement of energy performance.

Building services technology only began to evolve from the year 1850. The almost simultaneous development of installation technology and structures with steel or concrete frames and an unbound building shell made another type of architecture feasible. The role of the outer shell is less important because, with technical installations, great climate differences could be bridged. The social and cultural differences that accompanied them are remarkable.

As a result, in the course of history, architecture and climate technology have strictly developed separately in different domains. The role of the architect as an integral designer is thus eroded. The development of climate technology has given architects great architectural design freedom, but the art of science of building design in the context of heating, ventilation, lighting, and cooling is largely lost. Because of this, buildings have become much more dependent on building services and energy. Ironically enough, the satisfaction of users with the indoor climate is not proportional to this. The so called Sick Building Syndrome has mainly manifested in buildings with extensive climate installations.  Architects have, through the separately developed climate technology and their incompetence in this area, not uncommonly conceived a certain resistance to building services which is at odds with the integrated design.

The developments in energy savings are, to a great extent, part of the architectural past; there may even be clear rebound effects. The glass industry, for example, has reduced the thermal resistance of double glass to one third over past decade, however, architecture has seldom responded by tripling the glass surface.  The architect has, partly under the influence of increased social welfare and fashion, been further tempted to create exuberant shapes and building masses whereby the HVAC technology had to be summoned to assist in the realization of a quality indoor environment.

The mainstream development of architecture is only minimally or not at all concerned about the alignment of architectural design and the indoor environment in relationship with ambient climatic conditions and energy. 

“….The waning confidence of architects in their own ability to deal with energy problems (or opportunities) was increasingly manifested in the form of calls for a return to traditional modes of construction, inherited wisdom about location and orientation. Much of what was said was intelligent and well-founded, but most of what received publicity in those years now looks like paranoia. Rather than calling for more efficient air-conditioning, the call was for the abandonment of air-conditioning altogether, no matter who might suffer…”, (Reyner Banham in ”The Architecture of the Well-tempered Environment” ,1984).

On the other hand, it is unfortunate for HVAC engineers that they have studied very little in architecture, in which one of them lamented:

 “Six years of undergraduate, postgraduate and evening classes’ study at the University of Glasgow’s Faculty of Engineering…..had given me little exposure to architects, or even to architecture. A further 6 years at the University of Glasgow’s Building Services Research Unit had been little better in that respect. Not only did Banham’s book introduce me to architecture, but also it helped me throw off the engineering blinkers I had unwittingly been wearing for the previous 12 years….”, George Baird in “The Architectural Expression of Environmental Control Systems,  2001).

A short tour through history demonstrates that there has been criticism of the unilateral approach of architecture. Several examples of so-called climate active architecture indicate a turnaround and development in zero energy buildings and this will, undoubtedly, provide the necessary impetus.  A recent development in this area is the cradle to cradle philosophy of Braungart and Mc. Donough, advocates and practitioners of bioclimatic architecture.

What is a sustainable building?

According to Vitruvius, an architect and engineer from the Roman era, a building must meet the three qualities of firmitas, utilitas, venustas, i.e., ​​strength, utility, and beauty (Vitruvius 85-20 BC.).

A building based on the first and third quality requirements will not collapse prematurely nor rapidly deteriorate, thus, in principle, is a sustainable building. The second quality requirement is more time-bound and includes, in the 21st century, functionality, flexibility, and indoor environmental quality.

A contemporary Vitruvius would have  added a fourth to the three quality requirements: “responsibilitas” in which, besides energy efficiency, more general environmental, social, and cultural performance requirements would be included.

In addition to the standard measures within the scope of the Energy Performance Standards, anno 2012, an increasing interest can be observed for bioclimatic architecture and use of Responsive Building Elements (RBE).

The study Earth, Wind & Fire adds a new dimension: Climate Responsive Architecture.

Energy use

Research into energy efficiency of buildings over the last decades has focused on efficiency improvements of specific building elements such as the building envelope, including its walls, roofs, and fenestration components (windows, day lighting, ventilation, etc.), and building equipment such as heating, ventilation, cooling equipment, and lighting. Significant improvements have been made, and most building elements still offer opportunities for efficiency improvements.

However, the greatest future potential lies with technologies that promote the integration of responsible building elements (RBE) with the building services and renewable energy systems.  Responsive in this context indicates the ability to dynamically adjust physical properties and energetic performance according to changing demands from indoor and outdoor conditions. This ability could pertain to energy capture (as in window systems), energy transport (as air movement in cavities), and energy storage (as in building materials with high thermal storage capacity).

With the integration of responsive building elements, building services, and renewable systems, building design completely changes from design of individual systems to integrated design of responsive building concepts which should allow for optimal use of natural energy strategies (day lighting, natural ventilation, passive cooling, etc.) as well as integration of renewable energy devices (IEA Annex 44, 2010).

The following 5 RBE, whose perspective of improvement and widespread implementation in the building sector seem to be promising, are:

• Advanced Integrated Facades (AIF) such as, for example, ventilated transparent facades;
• Thermal Mass Activation (TMA), building elements used for energy storage;
• Earth Coupling (EC) such as, for example, foundation elements and buried ducts and culverts used to pre-cool or pre-heat the ventilation air;
• Dynamic Insulation (DI) such as, for example, breathing walls and roofs to pre-heat the ventilation air;
• Phase Change Materials (PCM): materials and systems integrated in building elements/installations to enhance their ability to store energy.

An integrated building concept, created through the synergy of Responsive Building Elements, HVAC services, and the energy system, allows optimal energy performance. This is illustrated in the figure below.

Trias Energetica

Energy conservation is ideally achieved by the Trias Energetica, a concept with which the sequence of three steps to the most sustainable energy supply is indicated:

1.            Reduce energy demand by applying measures to limit demand.

2.            Exploit the maximum sustainable energy sources such as wind and solar power.

3.            Use efficient techniques in order to completely utilize the remaining energy from fossil fuels.

Step 1 is, in  the Earth, Wind & Fire concept, realized by using measures from the repertoire of bioclimatic architecture including Annex 44. The usual heat recovery systems to reduce the heat demand are ineligible in this aspect. The climate at the workplace level is ideally performed with Low Temperature Heating (LTH) and High Temperature Cooling (HTC) systems, efficient control systems, and highly efficient pumps.

Step 2 is, in the Earth, Wind & Fire concept, on the one hand, is realized by direct exploitation of the environmental energy of earth mass, wind, and the sun. On the other hand, using the Heat and Cold Storage system and heat pumps, indirect utilization of solar energy is realized. The remaining energy demand sub step 3, including heat pump energy, is ideally realized by wind and the sun in the Ventec Roof.

Step 3: Classical techniques from the repertoire of building services include highly efficient boiler plants and combined heat and power with high exergy efficiency. However, the Earth, Wind & Fire concept targets zero energy;  therefore, these techniques are not generally required.

Bioclimatic Architecture

One of the founders of bioclimatic architecture, Victor Olgyay, has argued that building services  should only regulate the fine-tuning of the indoor climate which should be realized primarily by the building itself. The outdoor climate is tempered by the urban environment, situation, and vegetation upon which the construction site creates a microclimate. The building envelope and the building mass combine together with Responsive Building Elements for further attenuation. This creates a more natural climate control so the size of the HVAC system may be limited.

This concept goes beyond the fact that, through the heat-island-effect in urban areas, the microclimate at the construction site is often not lower than the outside climate but higher. Furthermore, a key feature of Responsive Building Elements, not demonstrated in the graph, is phase shift by absorption and desorption of heat.

Bioclimatic architecture focuses primarily on the architectural integration of systems for daylight, passive heating, natural ventilation, and cooling. The well-known bioclimatic architect, Ken Yeang, provides the following explanations:

• An ecological: the reduction of energy consumption and increase in the sustainability of buildings.
• A social: improving human welfare, especially in high-rise buildings.
• A cultural: continuation of historic buildings to human learning to adapt to the local climate.
  

Bioclimatic architecture is, therefore, as directed by Ken Yeang, not based only on the form, beauty, and usability of a building but also on its ecological, social, and cultural achievements. Initially focused on energy efficiency and sustainability, the integration of bioclimatic strategies thus serves another purpose as well, viz., promoting a high sensory and mental satisfaction for residents and users of the building by which their performance can subsequently be improved.

Conventional instruments from the architectural repertoire include layout, location and orientation, glazing percentage of the facade, execution of windows and blinds, thermal insulation and energy storage of the structure, etc.. Anno 2012 Responsive Building Elements (RBE) are added to this repertoire.

Climate Responsive Architecture

Bioclimatic architecture is capable of attenuating the influence of the external environment on the indoor climate, thereby limiting the required energy use of a building.  With passive measures alone, a thermally comfortable indoor environment in a building cannot always be realized. There is still energy required for climate control and the realization of a zero energy building, therefore, requiring further facilities.

Climate Responsive Architecture as discussed below in the Earth, Wind & Fire concept fills this gap by making use of the natural environmental energy in the outside environment and the earth mass. This is basically allowing the achievement of a zero energy building while avoiding adverse effects on the indoor environment.  According to this concept, a building is designed as a “CLIMATE MACHINE” activated by the combined forces of the sun, wind, and gravity.

Climate Responsive Architecture falls inside the broad spectrum of passive and low energy architecture, indeed, but should not be identified with bioclimatic architecture.

 “…a new-found creative collaboration between architecture and engineering can produce designs that combine logic and intuition in solving increasingly complex and demanding tasks” (Dean Hawkes in “Architecture, Engineering and Environment, 2002).

As Climate Responsive Architecture, the Earth, Wind & Fire concept links the HVAC design, building physics, and systems to an architectural statement. Through this holistic approach to the design process, the distance of understanding between architect and engineer is reduced, a primary objective of the study.

The architect is given, by axiom, a major role in the climate design and the energy efficiency of buildings. The climate features perform as elements for architectural expression, and climate technology is no longer subordinate to architecture but is, in itself, part of architecture. The design of a building as a climate machine is also a task whereby the architect also becomes partly responsible for the indoor climate and energy management. A great intellectual and artistic potential is thereby enabled for an intrinsically integrated design. This strategy also promises a potential improvement of the design and a reduction in the cost of failures.

Integral sustainability

Because of the limited availability of fossil fuels and the increased concentration of greenhouse gases in the atmosphere, energy is indeed a crucial environmental theme, but this includes more than just energy. In several countries, instruments have been developed in which the design of the overall sustainability of a building can be assessed. Points or scores with certain weightings are assigned to different aspects such as energy, water, material bound environmental load, the indoor environment, and the quality of the urban environment.

Instruments often employed in the Netherlands are Greencalc and BREEAM-NL, which will be integrated into BREEAM–LIGHT. Other instruments are Eco-Quantum and GPR-building. After employing these tools, some critical comments have been noted:

• As with the pursuit of a low EPC value, in this aspect, it is often easier and less expensive to also score with less durable installations than with the more expensive and more durable structural facilities which, subsequently, will be omitted.
• Important quality aspects are not included in the assessment. This applies, for example, to the functionality of the building for the users, the urban planning attractiveness as reflected in the quality of shops and public parks, and, finally, the “beauty” of the building itself.
• Feedback from measurements and experiences in the use phase to the assessment of the building in the design phase rarely occurs. Continuous adaptation and improvement of the systems and models based on practical experience is, therefore, difficult. This applies especially to energy use and CO₂ emissions which are key for reducing climate change.
• A building with a high score on sustainability and energy efficiency, even if validated in the use phase, may have neglected the most important aspect of architecture, specifically, providing a pleasant, healthy and productive workplace, a combination of well-being and design quality.
• Use of different instruments leads to different outcomes on the scale of sustainability.

A Holistic Approach

Climate Responsive Architecture is, in principle, applicable to any building design. Combined with bioclimatic architecture and a high environmental score, it also offers the greatest environmental benefits. Low energy consumption then goes hand in hand with integrated sustainability.

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