ASHRAE discusses obstacles faced with cold climates in HVAC design
A cold climate presents tough challenges for an HVAC designer or engineer as there are many additional considerations to account for during the design phase, such as: thermal enclosure, frozen precipitation, permafrost, wind, and thermal comfort, for example. In Canada, especially, these considerations become necessary in order to provide efficient and sound design that can withstand the harshness of the winter season but also the wide temperature ranges faced between sunrise and sunset during the fall and spring seasons.
In November of 2012, ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers), REHVA (Federation of European Heating, Ventilation and Air Condition Associations), and SCANVAC (Scandinavian Federation of Heating, Ventilation, and Sanitary Engineering Associations) co-sponsored the 7th International Cold-Climate Design Conference, which was held in Calgary, Alberta, and invited researchers, designers, engineers, and manufacturers to share papers and findings that could improve the indoor air quality (IAQ) and humidity and temperature performance, all while reducing the amount of resources consumed, in a building under cold-climate conditions. SCANVAC initiated this series of conferences back in 1994 in Finland in order to kick-start the discussion on adjusting our global building systems to the climate change we currently all face.
During the 2012 Calgary conference, however, an idea came forward for design guidance due to these impending challenges. ASHRAE used the idea to recently publish the “Cold-Climate Buildings Design Guide”. The guide covers a wide range of topics which also include: sustainability, building controls, commissioning, and considerations for HVAC design calculations, accompanied by a set of case studies specifically pertaining to buildings currently acting as design role models in severely cold climates. As Frank Mills, co-author of the guide, stated, regarding his newly published work: “We do cover the extreme cold climates very well, but we also have very useful information for any buildings which have heating for part of the year,” he said. “This covers a lot of climate regions – including Europe where I am.”
Some considerations from the ASHRAE committee regarding efficient operation and maintenance of cold-climate systems include: the proper sheltering of critical equipment for accessible servicing, considerations for excessive wind gusts and drafts that may affect intakes, the obstructive effect of frost on coils and condensing pipes, and considerations for using psychrometrics during the design phase for estimating all possible methods of heat loss in order to ensure appropriate thermal enclosure. Roof construction and accessibility is also very critical to account for, as sliding ice or frozen surfaces can easily become a hazard for the service contractor or become another cause of intake and hood obstruction. By developing this guide as a standard for cold-climate design, ASHRAE has taken the lead in allowing for these considerations to become more apparent as potential hazards, thus improving the overall safety and operation of these types of buildings.
These improved methodologies and models have demonstrated significant energy savings to owners and therefore should be taken into account seriously. Various members of the HVAC community are now looking into using energy savings analysis software that can accept common HVAC design parameters and information regarding the building operation, and be able to output a savings in dollar amount. This type of analysis is now highly regarded as building owners and operations managers tend to spend millions in excess on energy losses throughout their system yearly, depending on the case. They are also looking at the longer-term investment during financial decision-making. If more expensive equipment is needed for the construction of a particular laboratory, for example, it is considered wise to evaluate its greater reliability over a lesser product, which will cause greater operational expenditures and head-aches down the road.
Increased software capability, in terms of building automation and control, allows for constant system monitoring and ease of troubleshooting as well, again directly translating into savings. In order to keep up with the rapid advances in technology nowadays, building controls and systems must be able to adapt and have the potential to upgrade to higher platforms. The compromise between project budget and energy savings is a tricky balancing act, however, the pay-back period of these savings should always be considered. All in all, the more an HVAC designer or engineer considers the future use of the space during the initial planning and design phase of a construction project, the less has to be spent on a more costly potential retrofit down the road.