It seems all too often that when I first start making site observations of new construction, the same issues are observed for every one of my projects. Issues such as continuous vapor or air barriers, protections of ducts and equipment, or clearance allowed for insulation on piping or ducts. And, nearly every time I bring them up with the construction team, I get the same initial response from the contractors: “That’s how I’ve done it for 30 years” or “That isn’t a big deal.”
While I would like to argue that it doesn’t matter how long someone has done something if it is done wrong in the first place. Instead, I try and educate the team on why it is important to sweat these details that seem so trivial to the contractors. What the contractors fail to realize is that these issues will not present themselves quickly. Usually, they are issues that will take years to become an eventual problem, long after the contractors have left the site and the warranty period has expired.
Having been involved in many retro-commissioning projects, I have personally seen the kind of damage an issue, which seemed so innocuous at the time, could do. In some cases, a problem may never present itself. But, why even take that chance?
In 2009 CxGBS® was contracted to provide retro-commissioning services and provide recommendations for a historical building in downtown Charleston, SC. The building was beautiful and designed with the highest quality in mind when they were first constructed, but was now tasked to lower energy use. During my first visit to do an assessment and investigation of the building’s operation and overall energy efficiency, I began by interviewing the building operations manager. He was a retired military mechanic that was somewhat ornery, but friendly just the same. Having worked in the military, he was very knowledgeable in all things mechanical and comfortable operating the recently updated Building Automation System. During our interview, he told us about the steps made to make the building more energy efficient, such as adding demand based ventilation and replacing their old chiller with a state of the art chiller. We then moved on to the issues that he observed in his day to day operations. The overwhelming problem that he encountered was high humidity in the building. It was due to the high humidity that he ran the building’s HVAC system 24 hours a day, and still had trouble keeping the humidity down. With the building located so close to the coast, he said that the moisture would come through the walls and raise the humidity if he turned the HVAC system off at night.
He then directed me to all of the drawings and documents. After thoroughly reviewing all of the building information, we proceeded to each major piece of equipment to observe their operation. The majority of the building was served by a giant air handler filling an entire room. When we climbed up to the room that held this massive air handler, I noticed that an injection fan, which was also in the room, was not running. When asked why the fan was not running, the building manager said that the fan was ordered to be turned off by a company engineer, in an effort to save energy. Everything began to make sense. That fan that was turned off was responsible for supplying all of the ventilation air to the building. As a result of the fan not running, the building was now negatively pressurized. Rather than conditioning outside air by controlling its path into the building, humid outside air was infiltrating through doors and window cracks.
The moral of the story: training and documentation are keys to maintaining a building. In this case, as operations staff had turned over, the correct operation of the building was lost and resulted in a severe humidity problem.
Are Owners and Designers taking full advantage of energy simulation software? – By David Cantrill CxGBS®
Jun 9, 2011 Editorials
It appears that more often than not, energy simulations for buildings are being performed to satisfy requirements of the various sustainable rating systems in the industry today. What owners are looking for from the energy model is whether or not the building designed by the design professionals they hired will achieve multiple points under the rating system to help them in achieving a higher rating system threshold. Once these energy models are completed and submitted for review, they are typically cast off to the side and rarely dealt with again. The owner got what he wanted out of the model, so what is the need for it anymore?
The majority of these energy models are developed well after the design of the building has been completed. As such, there is typically no thought put into whether a different system or design could have resulted in a building with less energy usage than the current design. This is the first area where owners and designers are not taking full advantage of what an energy simulation can do for them. Designers who utilize energy simulation software during the design phase of the project can investigate multiple HVAC system designs, lighting designs and architectural designs to determine what combination can lead to a more energy efficient facility. This approach also allows the designers to present the owner with multiple options for the building design and allow the owner to get the “most bang for their buck.” Designers can see whether a water loop heat pump system or a simple variable air volume system is a more energy efficient system for the building they are designing. Though one system may appear to be more energy efficient than another, using an energy simulation program can give designers more confidence that they are choosing the most efficient energy system for the building.
Utilizing the energy simulation for measurement and verification of building energy usage is another area where owners are not taking full advantage of energy simulations. Many buildings experience increased energy usage years after the construction of the project is completed. Not knowing what is causing these increases in energy usage, owners are looking into energy auditing and/or retro-commissioning services to determine the issues and recommend ways of fixing them. By utilizing the energy simulation that was developed during the design phase of the project, the owner can keep tabs on the energy usage on a yearly basis and quickly determine when there are fluctuations in energy use and make changes or repairs as needed without hiring a third party consultant.