Principles of IBD

In literature, the Integrated Building Design (IBD) concept is also known as Integrated  Design Process (IDP) and Whole Building Design (WBD). While the common consensus is to state that European and North American professionals conceived this design concept in the 1980s and early 1990s as a holistic approach to design energy efficient buildings, it is more accurate to state that it was rediscovered after its initial formulation by the Roman Architect Vitruvious, circa 25 BC.[1] In his work, Vitruvious emphasized architectural designs that were adapted to the local weather as illustrated by the following passage from his “10 Books of Architecture”[2]: 

“If our designs for private houses are to be correct, we must at the onset take note of the countries and climates in which they are built . One style of house seems appropriate to build in Egypt, another in Spain, a different kind in Pontus,.....Thus, we may amend by art to correspond to the position of the heaven and its effect on climate”


The Thermae or Roman public baths provide an excellent illustration of the above passage. For their construction, Vitruvious directed the builders to locate the warm baths in the south-west portion of the building, with openings to public gardens and shaded avenues of trees and simultaneously allow natural light to enter the space, while the north-east side of the building, typically exposed to cold winds, was designed with no openings and a minimum number of doorways.[3]


Today, this approach is known as “A Weather Responsive or Weather Integrated Design”. This design philosophy takes into account elements such as building orientation, building shape, trees to protect from the winter winds and shade from the sun, local wind patterns to provide passive cooling, building overhangs to minimize solar heat gain, daylighting features to reduce electricity use and finally, good thermal performance to reduce the heating and cooling energy use. 


A striking example of the impact on energy performance from a weather responsive design philosophy is illustrated by the Mt. Airy Library completed by Ed Mazria in the early 1980s. Mazria, who in 2006 launched the 2030 Challenge, designed this building using a fully weather integrated approach that relied on passive cooling and heating, natural ventilation and a full daylighting design to achieve an overall energy intensity of 6.7 ekWh/ft².yr (263 MJ/m².yr) that is approximately 65 to 75% lower than current design practice. [4]


The multi-tower NMB Bank (now ING Bank) headquarters in Amsterdam built in 1987 provides another early example of the significant gains in energy performance that can be achieved through the whole building design concept. The head of design, Dr. Tie Liebe set the goal to build a collection of “organic” buildings that integrated art, natural materials, sunlight, plants, energy efficiency, low noise and water which resulted in a building complex with an overall energy intensity of 13.2 ekWh/ft².yr (512 MJ/m².yr) that, even for today standards, ranks among some of the best low energy building designs.[5]


Amory Lovins discussed the subject in the early 1990s and stated the need for designers to look at the building as a whole rather than the modern day practice of sequential design that came about with the introduction of air conditioning and ventilation systems. He repeatedly stated the need to design buildings “Right” by going back to basics and re-introduce the design process that had been used in the past. In the September 2005 issue of Scientific American devoted to climate change he further stated that [6]:


“Good design should rely on optimizing the whole building for multiple benefits rather than the use of isolated components. This is not rocket science; it’s just good Victorian Engineering rediscovered”  


Indeed, the construction industry is re-adopting this “Victorian” design philosophy as demonstrated by the re-emergence in the last 10 to 15 years of passive ventilation, as well as, passive heating and cooling designs. Professor Jeffrey Cook from Arizona State University provided a fitting parallel in a 1998 ASHRAE article describing the original design of the Natural History Museum in London England, which relied on a natural ventilation design via use of outside air inlets at ground level, coupled with six towers to induce air flow via natural convection.[7] Professor Cook stated that the design was:


“An example of forgotten knowledge that addresses

today’s interest in passive and low energy designs.”


While North American industry has not fully adopted the integrated design techniques and approaches that are fundamental to efficient construction and low energy buildings, the captivating appeal of IBD is unmistakable since it offers the promise of a higher quality design, better occupant comfort, lower energy use, lower GHG emissions and reduced operating costs, at minimal incremental construction costs. This feat of “achieving more for less” is possible because of two fundamental characteristics that are intrinsic to IBD:


1. Larger Energy Savings: One of the main goals of the design approach is the minimization of loads and HVAC equipment size. This load minimization compounds the energy savings compared to the savings that can be achieved from more traditional introduction of standalone energy efficiency features. The larger energy savings are achieved because the design optimization of one component induces energy savings in other components. An example would be an efficient lighting design that results in a very low internal heat gain, which produces additional cooling, fan and pump energy savings.


2. Marginally Higher Incremental Costs: Properly applied IBD will result in smaller HVAC and electrical components and lower first costs that can be used to offset the incremental cost of energy efficient components. As an example, adding heat recovery and a condensing boiler will provide some improvement in energy performance, but will have a higher incremental cost. However, improving the thermal performance of the envelope and reducing the amount of glass will reduce the design heat loss and size of boiler, which in turn will provide a minimized incremental first cost. [8]



Contrary to some literature that suggests a complex organizational process, IBD is a straightforward design process that does not require sophisticated technologies. The approach can be broken down into four fundamental steps that include: (1) minimization of HVAC and lighting loads; (2) use of equipment with the highest available efficiency; (3) optimization of operation, and (4) commissioning to ensure that the equipment operates as originally intended.[9] A flow chart of this design process that starts with architectural optimization and advances to commissioning is included in the “IBD Process” page. Design features at each of the four stages are also listed next to each major step.


From a “critical path” standpoint, the load minimization is the most important step and requires integration of the architectural design with the mechanical and electrical designs. Additionally, a higher level of rigor and precision in the design process is required to avoid the use of default values, "rules of thumb" and recognition that peak loads, especially for cooling need to include load coincidence.


It is also important to recognize that IBD relies on quality designs rather than least cost designs, but because of the trade-offs intrinsic to the process, the resulting design may not be significantly more expensive. From an architectural perspective, the goal to minimize the loads requires a highly insulated envelope including high performance glazing systems plus other design features and technologies shown in the accompanying graphic. These design features and technologies apply to both heating and cooling dominated climates. Other architectural features that can provide further functionality and comfort such as increased use of natural lighting are equally important. The HVAC and lighting designers have similar objectives to also minimize the size of the equipment through the use of good design principles, avoiding excessive equipment oversizing and selection of most efficient components with the ultimate goal to achieve design metrics similar to those listed in the graphic.

From the above description, it can be inferred that the IBD concept is not complex, yet it is misunderstood and shrouded in convoluted language with most available literature describing a complicated project management process, but little guidance on the actual “How To Design” elements necessary to achieve a low energy design. The result of this lack of understanding is that, despite having additional professionals such as energy modelers and LEED facilitators, the design, as stated by Adrian Tuluca in a book he published in 1997, ends up having [10]:


“Energy Efficient features simply pasted on a traditional

design late into the design development”


To add further confusion, in the early days, energy efficient construction was mistaken with complex designs and “Intelligent Buildings”. One program from the mid 1990s for example, proposed achieving low energy building designs through “adoption and promotion of advanced technologies”.


Unfortunately, this was still the case in 2008 when the New Buildings Institute prepared a report compiling the performance of 121 LEED projects which exhibited an average energy performance that was approximately 28% better than ASHRAE 90.1-1999.[11] In 2009 the World Business Council for Sustainable Development (WBCSD) stated that present policies and financial barriers are only achieving small incremental improvements in building performance.[12] Finally, an energy benchmarking study of Canadian commercial office buildings released in 2012 by REALpac showed that office buildings built after 2000 had an average whole building energy intensity of 29 ekWh/ft².yr (1,120 MJ/m².yr) compared to 31 ekWh/ft².yr (1,200 MJ/m².yr) for the entire sample of Canadian office buildings, representing an energy performance improvement of only 6%. [13]


However, there has been significant acceleration in activity and efforts to improve the energy performance of commercial buildings by numerous entities and organizations world wide including the US Green Building Council (USGBC), the US Government through its various laboratories, ASHRAE, CIBSE, REHVA, Intelligent Energy Europe (IEE) and others.[14] [15] In particular, ASHRAE has embarked on activities to aggressively address energy efficiency in buildings including the continuous updates of established energy standards such as Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings plus development of newer, more stringent standards including Standard 189.1 Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings and the Advanced Energy Design Guides (AEDGs) designed to provide 30% and 50% improvements in energy performance over Standard 90.1 via increasingly higher prescriptive guidelines.


At present though, the European Union (EU) enjoys a significant lead over North America with a large portion of their building industry having adopted low energy design practices including a reported 25% penetration of Displacement Ventilation (DV) designs in Northern European office buildings approximately 10 years ago and coupled with radiant cooling panels (chilled beams), considered to be conventionald design practice in Germany.[16] [17] These types of HVAC systems allow the design of commercial buildings with low energy intensities as demonstrated by building codes such as Norway’s proposed building code for 2012 (TEK12), which requires that non-residential buildings exhibit an energy performance of 110 ekWh/m².yr (~10 ekWh/ft².yr) and France’s regulation RT2012, mandating a maximum primary energy intensity of 50 ekWh/m².yr (4.6 ekWh/ft².yr) for non-residential buildings.[18] These aggressive energy performance levels are consistent with the findings from a report from the American Council for an Energy Efficient Economy (ACEEE) released in 2012 that rated the energy efficiency of the 12 largest economies and ranked EU buildings higher than North America buildings with particular emphasis on German and UK buildings having one of the lowest building energy intensities.[19] These levels of performance are driven by multiple factors including the concern for energy security, stringent building codes and a commitment to significant cuts in CO2 emissions in order to meet the EU’s GHG emission targets by 2020. As a result, the EU created the Energy Performance Building Directive (EPBD) in order to legislate large improvements in the energy performance of existing and new buildings which the European Parliament passed into force on May 2010 as Directive 2010/30/EU.[20] Among other things, Article 9 of the Directive requires that by 2020 all new EU buildings be designed to be “nearly zero energy” while government buildings are required to meet this criteria by 2018.


China is similarly, showing a political commitment towards aggressively pursuing energy efficiency. For example, in 2009, the central government announced a voluntary program to cut CO2 emissions in 2020 by 40 to 45% of the 2005 levels, signaling that energy efficiency is becoming critical to the economy.[21] While there is a significant amount of work that needs to be done to address fundamental issues such as lack of insulation in most commercial buildings, there are some very impressive high profile projects such as the 71-storey Pearl River Tower completed in 2011. This 2.3 million ft² (~215,000 m²) office building is reported to be nearly net zero, combining designs features that include a double skin façade, underfloor ventilation, radiant cooling and heating systems plus a host of renewable technologies which gives the building the distinction of being labeled as the most energy efficient super-tall building in the world and the largest radiant-cooled office building in the world. A more impressive project though will be the prototype Chengdu Tianfu District Green City; an entire city project capable of housing 80,000 people and designed as a self-sustaining city with a projected energy use that will be 48% below that of a conventional city. The city is being designed as a modular project that can be replicated across China with a planned construction start in the fall of 2012. If successful, the project promises a blueprint for the creation of energy efficient cities in "one-go" as opposed to just individual energy efficient buildings. [22]


















[1] Further reading on the history of the modern day IBD concept can be found in the 1996 ASHRAE article and the 1998 EEBA Conference paper located in the “References” page.


[2] "De Architectura", the Ten Books on Architecture.


[3] Energy Conservation Design Resource Handbook, Royal Architectural Institute of Canada. 1979. Ottawa.


[4] Project profile of the Mt. Airy Public Library. Accessed at


[5] Romm, J.J., Browning, W.D. 1994. Greening the Building and the Bottom Line. Snowmass, Colorado: Rocky Mountain Institute


[6] Lovins, Amory. “More Profit with Less Carbon “. Scientific American, September 2005.


[7] Cook, J. 1998. "Designing Ventilation with Heating - Natural History Museum in 1873 London" ASHRAE Journal, Atlanta Georgia: ASHRAE. Vol. 40, No. 4, April, pp. 44-48.


[8] Further discussion of cost trade-offs can be found in the 2004 ASHRAE article and the 2006 EIC Conference Paper located in the "References" page.


[9] Additional description of the IBD concept can be found in the 1996 ASHARE article and the 1998 EEBA Conference paper located in the "References" page.


[10] Tuluca, A. 1997. Energy Efficient Design and Construction for Commercial Buildings. McGraw-Hill, N.Y.


[11] Turner, C., Frankel M. 2008. “Energy Performance of LEED for New Construction Buildings” New Buildings Institute. March 2008.


[12] Energy Efficiency in Buildings - Transforming the Market. World Business Council for Sustainable Development, 2009. Accessed at


[13] 2012 Energy Benchmarking Report: Performance of the Canadian Office Sector”, Real Property Association of Canada (REALpac). Accessed at


[14] Chartered Institution of Building Services Engineers (CIBSE)


[15] Federation of European Heating, Ventilation and Air Conditioning Association (REHVA) 


[16] Hamilton, S.D., et al. 2004. "Emerging Technologies: Displacement Ventilation” ASHRAE Journal, Atlanta Georgia: ASHRAE. Vol. 46, No. 9, September, pp.56-57.


[17] Design Brief - Radiant Cooling, Energy Design Resources. Accessed at


[18] Jagemar L, et. al “Towards nZEB – Some Examples of National Requirements and Roadmaps” REHVA Journal, May 2011, pages 14 – 17.


[19] Hayes, S., Young, R., Sciortino, M. 2012 "The ACEEE 2012 International Energy Efficiency Scorecard". Report Number E12A, ACEEE.


[20] Directive 2010/31/EU of 19 May 2010 on the energy performance of buildings. Accessed at


[21] China to cut 40 to 45% GDP unit carbon by 2020. Accessed at


[22] China is building a Brand New Green City from Scratch. Accessed at:


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