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Low Energy Buildings – Transforming HVAC Design to an Art

posted Jul 12, 2020, 6:08 AM by   [ updated Jul 12, 2020, 6:35 AM ]

Painstakingly forging three hundred layers of steel. That is what it takes to create Damascus steel that exhibits legendary hardness, ease of sharpening and the characteristic patterned banding that gives Damascus steel its beauty. It is extreme craftmanship only possible with attention to detail.

Low energy buildings share similarities. As a prerequisite towards net-zero and carbon neutral buildings, low energy buildings embody attention to detail, and a minimalist design elegance that can only emerge through application of a whole-systems approach to optimize the overall design. Amory Lovins [1] referred to this in a 2005 Scientific American article titled ‘More Profit with Less Carbon’ as: 

“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”

As we know, this whole building design concept refers to the integrated design process (IDP) or integrated building design (IBD) that focuses on systematic load minimization that can only be achieved via a true interdisciplinary team effort that starts at the conceptual design stage.

Today, climate change and the increasing frequency and intensity of extreme weather is fueling a demand for climate adaptable and resilient buildings. Low energy buildings exhibit such attributes because they exploit the symbiosis that exists between a building envelope and a building’s mechanical system that, taken to an extreme, can border on nothing less than transformational wizardry.

Imagine a new high-rise office building shaped in an elegant, post-modernist or classical revival style. Such styles emphasize mass and less glass over the more ubiquitous all-glass International Style that is finally being recognized as incompatible with today’s sustainable buildings.[2] [3]

Our low energy building would exhibit recessed punched windows with a window-to-wall ratio (WWR) under 30% that is below the maximum ASHRAE 90.1 or the 2017 NECB values. In a heating dominated climate like Ottawa or Montreal, the building would incorporate high performance glazing systems and a highly insulated envelope with the far-reaching and unconventional goal to eliminate the need for perimeter heating. Minimal heating would still be needed, but only at peak winter design conditions and met with temperate air through an underfloor displacement ventilation system serving the building perimter.

That same envelope would also exhibit lower solar heat gains and cooling loads thanks to proper specification of low solar heat gain coefficients (SHGC). In turn, these features would allow selection of small, semi-passive ventilation systems based on dedicated-outdoor air systems (DOAS) plus passive chilled beams, resulting in an unobtrusive and minimalist design. Gone would be the ubiquitous all-air ventilation systems with ceiling diffusers present everywhere and served by large air handling systems. To be sure, such a design would be a paradigm shift in North American design practices, but needed in the face of escalating climate change urgency.

Beyond the lower operating cost, lower carbon footprint and minimalist elegance of such a design, there would be countless benefits not readily apparent including: increased comfort afforded by the warmer surface temperatures of exterior walls in winter and lower heat gain in summer; superior air quality and removal of contaminants via the displacement ventilation system; more moderate lighting levels and less glare near the building perimeter thanks to the smaller glazing which would unexpectedly and surprisingly, result in a higher amount of daylight since blinds would likely stay up.

 All in all, a design that subscribes to the old maxim that “less is often more” and the notion that simplicity leads to good design, or as Leonardo da Vinci said:

"Simplicity is the Ultimate Sophistication"

[1] Lovins, A. “More Profit with Less Carbon”. Scientific American, September 2005. Accessed at:

[2] It’s time to Rethink the All-Glass Building. Accessed at:

[3] Are architects turning their backs on glass skyscrapers?. Accessed at:

The Right Stuff to Achieve Truly Improved Building Energy Performance

posted Jul 28, 2019, 12:58 PM by   [ updated Jul 29, 2019, 6:11 AM ]

On Saturday July 20, I was having breakfast in the backyard, reading the newspaper. It was still early enough that the temperature was pleasant and the air fresh, unlike the furnace-like conditions that were expected later that afternoon.

The newspaper had quite a few articles on the Apollo 11 mission in commemoration of the 50th Anniversary of the Moon Landing. One, written by Basil Hero, titled “Searching for the Right Stuff” struck a chord. Hero stated that one of the elements of “the right stuff” is the pursuit of the “common good”, which is rooted in ancient Greece where their citizens believed not in living just for themselves, but for the community. Towards the end of the article he stated that: 

If there is any lesson learned on this 50th anniversary of the moon landing, it should be 
that humans find the right stuff to pursue the  common good of Planet Earth

To me this is powerful stuff. It is readily applicable to the design of low energy buildings and the urgency, Real Urgency to ensure that new and renovated buildings exhibit minimum energy use and GHG emissions in order to combat Climate Change. 

Despite the increasing rhetoric on net zero and carbon neutral construction and the fact that we have been at it for some 25+ years since the days of the Savings-by-Design program from Ontario Hydro back in the 1990s, our track record reducing building energy use, especially in North America, is mediocre. Don’t take it from me. Go and download the 2017 RealPac report (1). It’s a large database of Canadian office buildings with a sample size of ~430 buildings, encompassing some 129 million ft². You will see that buildings constructed after 2000 show a slight improvement of only 22% from the average of 32 ekWh/ft².yr down to about 25 ekWh/ft².yr (1,240 to 970 MJ/m².yr). This is consistent with what Joe Lstiburek stated in his 2008 article “Prioritizing Green – It’s the Energy Stupid” (2),(3). He reported on a 2008 study that compared the energy performance of sustainable buildings against  conventional construction. The study, conducted by the New Buildings Institute (NBI) found that on average, the sustainable buildings were approximately 15% better than conventional construction.
So what‘s going on? We keep building them the same. First due to financial barriers in terms of consultant fees, as well as, construction costs. The majority of consultants will go for the tried and true, which can be achieved with minimal effort. Whereas a new design away from conventional VAV and our North American fixation with all-air, overhead delivery systems would require more effort, even though it’s debatable whether more effort is required to design say, a DOAS+chilled beams, but I digress. Higher construction costs come into play when contractors will see a higher level of risk to install something that is not familiar to them and then, there is the common practice of slapping a premium on high performance construction. 

Risk aversion towards new technology is another impediment that comes into play. Critics will say though that the industry is not averse to embracing new technology as VRF technology is gaining market share. But then we are doing nothing to reduce the loads; to create climate adaptable, well insulated buildings with reasonable amounts of glazing. 

So, what’s being built is the same high rise office building or condo with an all-glass envelope that requires large amounts of heating and cooling, served by more modern technology such as VRF or water loop heat pumps. The result, as attested by the RealPac database and Joe Lstiburek, is buildings that are only marginally more efficient than their 1980 or 1990 counterparts. 

If we want to make a difference though, we ought to be designing and constructing buildings that, from the get-go, have a minimal need for heating and cooling, which will allow drastically downsized HVAC systems; an absolute prerequisite towards net zero. 

In his article, Hero also stated that: 

We once did the impossible. We can again.

It’s time to have the courage to do the impossible in the design and construction of buildings. Let’s pursue The Right Stuff towards the common good of Planet Earth.

2. Lstiburek, J. Building Science Insights “BSI-007: Prioritizing Green – It’s the Energy Stupid”. 10/28/08. Accessed at .
3. Lstiburek, J. 2008. “Why Green Can be Wash” ASHRAE Journal. Atlanta, Georgia: ASHRAE. Vol. 50, No. 11, November, pp. 28-36.

Are Mainstream Low Energy Designs in the Horizon?

posted Feb 15, 2016, 5:51 AM by   [ updated Feb 15, 2016, 6:40 AM ]

The 2015 United Nations Climate Change Conference known as COP 21 that ended on December 12 reached its objective of a global agreement to reduce GHG emissions. It was hailed as a success even though it only becomes legally binding once it is signed by the 55-55 (the 55 nations that account for 55% of total GHG emissions).

Critically though, the agreement calls for aggressively tackling GHG reductions immediately in order to reach Net Zero emissions in a couple of decades. Some readers will notice that this is more or less in line with the goals from ASHRAE, the 2030 Challenge and the EPBD from the European Union, although the EPBD target for reaching Net Zero is 2020.

The year 2015 was confirmed to be the warmest on record and 2016 is forecast to be warmer with an average global temperature of about 1°C higher than the average thanks to El Niῆo.(1) Unbelievably warm fall and early winter weather was recorded here in Ottawa. In fact, December had the warmest weather since record keeping began. To me, all this signifies that the urgency for an immediate reduction in GHG emissions is warranted.

So the big question is whether the above commitments and calls for immediate aggressive reductions will change the way we build buildings. I am hoping that it will, but unfortunately, I still see a reluctance from the industry to turn design and construction on its head, away from “Value Engineering”. We continue running in circles because I still hear the same things including:
  • Developers who still want to build ‘em cheap, but still meet SB-10 (the Energy Supplement of the Ontario Building code). It seems to matter little how many articles are written on the true costs of high performance buildings that point to small or no incremental costs thanks to the concept of tunneling-through-the-cost-barrier.
  • Project managers of institutional buildings who want to undertake a midlife refit of a building using tried and true technology with minimal impact to the overall carbon footprint of the building. They fail to understand that the renovated building is going to operate for another 20 or 30 years with essentially the same carbon footprint, a lost opportunity. This is not just me saying it. Back in 2009, ASHRAE president elect, Gordon Holmes said that energy efficiency in existing buildings is our greatest opportunity because less than 5% of construction projects are new construction, while the rest are existing buildings.(2) Buildings built between 1960 to 1980 account for the largest portion of the built environment and many of them need to undergo a mid-life refit.

  • Lack of knowledge that takes many forms from understanding the effective thermal performance of spandrel panels to making ludicrous statements like DV and UFAD systems provide very poor IAQ because the registers/diffusers are on the floor or wall and bring up dirt into the breathing zone. So new designs continue to be mostly overhead mixing systems, even though DV + Radiant Cooling are pretty well standard practice in some parts of the world such as the EU and most of our houses use floor delivery system.  

The weather is telling us that it is time to wake up. In saying this, I am also reminded of what Jared Diamond said about failed civilizations in his 2005 book Collapse:  “Failure of societies and civilizations has happened repeatedly because of the baffling phenomenon of failures of group decision-making and idleness in the face of disaster.” (3) 

 I really hope that the industry’s commitment to widespread design and construction of Low Energy Buildings is not too far away.

(2) Holmes, G. “Sustaining Our Future by Rebuilding Our Past”. ASHRAE Journal. August 2009.
(3) Diamond J. “Collapse: How Societies Choose to Fail or Succeed.” Page 420, Chapter 13.

It’s Not Business as Usual

posted Jan 28, 2015, 5:19 PM by   [ updated Feb 15, 2016, 6:20 AM ]

I was reading an article in the Jan. 14 Ottawa Citizen newspaper about the Province of Ontario’s 2014 Annual Energy Conservation report released by the Environmental Commissioner that states that efforts to reduce electricity use and electrical demand are falling short of expectations (1). The article stated that utilities in Ontario have had targets to reduce peak demand and overall use, but almost all electric utilities will miss the peak demand targets and half will miss the overall consumption targets. The official press release said as much and more alarmingly, it stated that public interest in conservation in Ontario seems to be at an all-time low. This is of especial concern in the face of the troubling news that we have been receiving of late including the fact that 2014 was the warmest on record with the highest recorded GHG emissions. Canada also ranked last in the industrialized world in terms of climate change record as published by Germanwatch (2) (3).


Improving building energy performance would greatly help to address all the above issues, yet after more than a decade of green construction activity, large improvements in building energy performance seem elusive. This lack of significant improvements in performance is described elsewhere in this site and evidence continues to mount including:


·         green building programs that show that the participants’ building energy use and intensity shows little improvement;

·         the same green building programs that shows participants achieved very small or no electrical demand reduction;   

·         a study that reviewed energy efficient high rise condominiums constructed in Southern Ontario between 2010 and 2012 that concluded that the energy performance of many of those buildings was similar to buildings built in the 1970s.


It should not be business as usual, yet the design and construction industry is still operating like it is business as usual and squandering away the opportunities for deep cuts in energy and demand use, especially for new construction and major renovations. The culprits are well-known and already highlighted throughout this website, with the principal one being the propensity by designers to choose performance based approaches and trade-off design alternatives. The general held belief is that energy modelers will achieve savings despite a poor building envelope, high WWR, air handling systems with excessive connected fan power, -despite the clearly defined fan power limitations (90.1-1999 ECB or 90.1-2007 Appendix G)- and on and on. And let’s not forget that equipment sizing for all these so called sustainable buildings shows little reduction because no effort has been made to reduce loads. So in the end, if it looks like a duck, walks like a duck and quacks like a duck…..


The sad part is that 10 and even 15 years ago, well known industry leaders like Ed Mazria, Amory Lovins, William McDonough, Adrian Tuluca, heck even Prince Charles, were making similar statements about poor building envelopes, lack of true design optimization and using gimmicks and fads to replace good design. Back then though the sustainable green building design movement was just getting started, so the industry could use this as an excuse, but not today, especially when achieving a low energy design is simply quality designs, paying attention to detail and doing the load calcs. right. 


Oh, there are some great examples out there, but these are far and few in between and the impact at the aggregate level is not there and the bottom line is that we are barely improving.


(1)     Ontario’s Power –shortage crisis. Jan. 14 Ottawa Citizen

(2)     Crunching the numbers. Jan 6 Ottawa Citizen.

(3)     Climate Change Performance Index 2015 at

Four Key Design Steps to Achieve Successful Low Energy Designs

posted Feb 2, 2014, 12:50 PM by   [ updated Feb 2, 2014, 1:23 PM ]

Efficient building designs with performance levels below 20 ekWh/ft².yr (775 MJ//m².yr) can be attained with relative ease and low energy building designs below 12 ekWh//ft².yr (465 MJ//m².yr) can also be achieved through extreme load minimization coupled with alternative HVAC systems such as CC + DOAS and CC/DV. In North America, these performance levels are not being reached as frequently as the industry would like as evidenced by market studies and energy benchmark data. There are a number of reasons for this ranging from key decisions that are made at the early design stages to the design process itself.


Four key steps are described below that can help overcome the barriers that exist today and make low energy designs commonplace.


Start with a Solid Set of Design Specifications: In too many green building projects the minimum prescriptive requirements are ignored in favour of performance based designs that rely on trade-offs. While performance based approaches provide flexibility, they cannot be over-emphasized over minimum prescriptive requirements. A building with a weak envelope that has too much glass will have large heating and cooling loads and fan sizes and penalize the overall building energy use and peak electrical loads. To avoid this problem, the design team needs to start the project with rigorous design specifications for the thermal performance of the building envelope and glazing systems, reasonable window-wall ratios (WWRs), low lighting power densities (LPDs), careful selection of air handling equipment to minimize fan power requirements and finally, use of high efficiency equipment. The ASHRAE Advanced Energy Design Guides (AEDG) series of publications are an example of design guides that provide demanding prescriptive guidelines to achieve 30% and 50% energy savings relative to ASHRAE 90.1.These guides provide prescriptive tables that are differentiated by climate zone and building type.


Bundle Technologies & Components Together with the Objective to Minimize Loads: Bundling as many technologies as possible is particularly important for aggressive design targets that require significant minimization of loads. Such designs require that all building components work together because of the symbiosis that exists between the envelope and HVAC equipment. As a result, an overall good thermal performance of all components is needed, not just for some components. As an example, triple pane windows are very costly, if analyzed in isolation, but bundled together with a highly insulated wall will achieve significantly better returns on investment and a lower project cost thanks to the concept of “Tunneling-Through-the-Cost-Barrier”. This occurs because the highly insulated envelope allows a drastically reduced perimeter heating system and heating plant, in turn offsetting the incremental costs of the windows and better envelope.


Solid Design Process: It is not only about technologies, or performing energy modeling that will result in a low energy building design. The design approach together with paying attention to reducing the loads, performing accurate load calculations and careful selection of equipment are just as important, if not more important. Enough time and resources need to be allocated to do proper load calculations without adding safeties upon safeties or relying on default values. The effective wall and overall window Uvalues need to be properly calculated and the SHGC or SC of the actual window selected; not a default value. Attention needs to be paid to equipment selection, and in particular, specifying air handling equipment with air velocities below 400 ft/min (2 m/s) instead of the traditional 500 to 600 ft/min (2.5 to 3.0 m/s). This can be achieved by specifying slightly larger air handlers with increased coil surface areas. Such a reduction in air velocities can decrease the total internal static pressure at the air handler by upwards of 0.5 in. (125 Pa) and help reduce fan size by 15% or more.


Move Away from Value Engineering & Speculative Designs by Selecting Good Contractors and Getting Suppliers and Contractors Involved in the Design Process. This is perhaps the most difficult step to implement. Low energy designs rely on quality designs rather than least cost designs, but because of the equipment downsizing, there are cost tradeoffs that allow the design cost to be similar or only marginally more expensive then a speculative design.  Good contractors need to be selected and engaged early in the design process for these cost advantages to materialize. Similarly, equipment suppliers also need to be included in the design team to provide proper equipment selections and cost estimates to the contractors during the design stage. This will avoid the problems of equipment substitutions during the construction phase that frequently plagues projects, as well as, limiting or eliminating incremental costs for components and equipment that do not normally exhibit any, but do require custom selections. 

A Tale of Two Buildings

posted Dec 28, 2010, 8:57 AM by   [ updated Feb 2, 2014, 12:52 PM ]

It was the worst of times, it was the best of times, it was the age of wonder, nanotechnology, the Large Hadron Collider and the promise of Net Zero. It was the epoch of Intelligent buildings and buildings with two much glass. It was the season of GSHP and all sorts of advanced technologies bolted on. In short, efficiency was only a notion with some buildings performing marginally better, but most staying the same because they were designed with 40% to 50% WWR, a curtain wall displaying a poor thermal performance plus air handling units and heating/cooling equipment with unexceptional levels of performance.


However, the promise of better energy performance only requires a building with masonry wall construction incorporating good thermal performance plus a low WWR design with punched windows that are recessed to shade from the summer high angle solar heat gain, roof overhangs and careful selection of HVAC equipment.


As shown in the “Architectural Elements & Building Envelope” page these design elements can help reduce the heating and cooling loads by anywhere between 30% to 50% and simultaneously reduce the whole building energy use by approximately 30% without having to resort to advanced technologies. Adding “best-in-class” efficient lighting designs, which only require careful design and selection of appropriate lamp-ballast combinations (see the “Lighting & Daylighting” page) can provide an additional reduction in cooling loads together with a significant reduction in electrical peak demand.


Last, but not least, meeting the reduced loads with “best-in-class” HVAC equipment that is properly sized can help achieve overall energy savings as high as 50%, if based on HVAC designs such as CC + DOAS or CC/DV which are described in the “Efficient HVAC Equipment” page.

Introducing the Low Energy Buildings Website

posted Dec 28, 2010, 8:48 AM by   [ updated Feb 3, 2013, 12:22 PM ]

Welcome to the Low Energy Buildings website. You will find a discussion of the Integrated Building Design (IBD) process and design approaches to achieve low energy designs, supported by load calculation and energy simulations. There is also further reading including downloads of ASHRAE articles and conference papers that I published over the past 15 years.


Many professionals in the industry constantly remark that a large percentage of green buildings do not deserve the designation because the few technologies that they incorporate were simply added standalone, instead of integrated into the overall design or more frequently, the designs simply relied on "eco-gadgets" over good design. I submit that an important reason for this is the lack of simple documentation on how to build energy efficient and low energy buildings using design approaches such as Integrated Building Design (IBD). Another reason relates to the lack of understanding of load minimization concepts, including the critical importance of the architectural design to achieve significant reductions in heating and cooling loads or the tendency to specify too much glass, which affects the overall building energy performance in both heating and cooling dominated climates. In this respect, consider for example, that the ASHRAE Advanced Energy Design Guides (AEDGs), recommend maximum WWRs of 40%, for offices and 35% for schools, yet significant numbers of new commercial buildings, including office buildings and high rise condominiums, are built with much higher WWRs, sometimes due to aesthetics (Steel and Glass Designs), but also because of the false and misguided belief that large expanses of glass are an implicit requirement of daylit designs.


Lastly, there is a lack of understanding of the magnitude of energy savings that can be achieved through more efficient designs or how difficult it is to achieve savings greater than 50%. The majority of high performance buildings built in the last 15 years achieved improvements of 25 to 35% and a report released in 2008 by the New Buildings Institute (NBI) compiling the performance of 120 LEED projects found the average performance to be approximately 28% better than ASHRAE 90.1-1999.


I perceive the above issues and others like them, impediments to the more widespread design of low energy buildings, which ultimately prompted me to create this website. I hope that you will find the information contained within this site useful.


Giuliano Todesco

February 2013, Ottawa


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