HVAC-Specific BIM Offers Detailed Results
Right now that means Building Information Modeling, or BIM, a trend of increasing popularity among mechanical contractors, as well as the engineering and design community. BIM essentially allows buildings to be built digitally based on design information, in a 3-D format that shows interactions and errors, long before a bulldozer is booked for the jobsite.
Don McLean, founder and managing director of IES, is fond of quoting Lord Kelvin: “If you cannot measure it, you cannot improve it.”
“I’ve been involved in building analysis for 30 years,” said McLean, “and I’ve seen that by being able to quantify performance, you can optimize it. We believe that’s a very true statement.”
“When you try to do an analysis, you want to understand what’s going on,” McLean said. “The information can intimidate people. In sustainable design, we’ve got to get over that. The objective here is to try from the concept stage.”
Using BIM at the earliest possible stage of the design process, he said, is where it has the most profound effect. From there the entire design team, from the engineers to the subcontractors and the owner, can understand what’s the best building design for that building’s climate.
The company’s Virtual Environment (VE) software suite helps identify anomalies, and allows system designers to speculate on certain design parameters, and view their effects on building performance, without committing to something that could be a costly mistake, in both the short term and long term. What if the system is oversized? What if it’s 10 percent undersized? It also allows owners to see the energy-specific effects of their system choices.
“In the UK market, what’s happening is that a lot of the contractors are picking up the software to do the more detailed stuff, make decisions or adaptations that maybe the design team didn’t know about,” said McLean. “A lot of contractors are trying to insist that BIM is used.
“To some extent they are pushing BIM,” he said. “They want this model, and they check that what they are using is right, and they can bring to the client a better end product.”
It also has been used a lot in public-private partnerships, McLean said, where the contractor has some ongoing partnership in the building. “It has been the main driving force in the UK and other areas.”
“In the UK we talk about integrated design,” he said. “The contractors have been leading that for quite a long time - how to make a more integrated process.” They could see the advantages of modeling, he said, “reducing problems and creating a better product.
“I’m passionate about educated design,” McLean said. It has an impact on the engineer, contractor, and eventually the user. “Contractors are trying to overcome many of the design problems, drawings not matching up, making changes. Having a 3-D visual is something contractors want to be very active in,” he said.
There are multiple sustainability advantages for the United States, McLean continued. “Many Northern states have very nice climates for example, perfect for matched ventilation.” Using a BIM program allows designers to try to design a building to be more sustainable, “knowing what you need and what you want. Any system in there has got to have a symbiotic relationship with the building.”
HVAC APPLICATIONSThe company’s ApacheHvac is an HVAC plant modeling and simulation program, part of its VE product. According to the company, “it offers almost unlimited flexibility in system configuration and specification, and its detailed thermal simulation results in accurate carbon and energy figures. You can analyze system performance, see how the plant interacts with the building, and assess thermal comfort.”
The program can simulate HVAC systems using a flexible component-based approach that lets users assemble systems on-screen as designed. It covers all common system types including VAV, CAV, fan coil, VVT, displacement ventilation, hollow-core slab systems, and under-floor heating.
The program is dynamically integrated with the IES building simulation software (ApacheSim) for reliable estimations of plant sizes, optimization of the plant/controls operation, and accurate assessment of carbon emissions.
The principal application areas for ApacheHvac are HVAC system design, component sizing, HVAC control design, mixed-mode system design, energy consumption prediction, carbon emissions, building regulations, and CFD boundary conditions.
Components include heating and cooling coils, fans and dampers, mixing boxes and economizers, steam and spray humidifiers, heat recovery, duct heat loss, room conditions, radiators and chilled ceilings (dynamic model), direct-acting heaters and chilled beams, controllers sensing temperature, humidity, enthalpy, flow rate, solar radiation, controllers sensing the difference between two variables, on-off and proportional control, cascaded control logic, and boilers, chillers, and heat pumps, including ancillary pump and fan consumptions.
Earlier this year, the company announced a partnership with Gaia Geothermal to offer a joint package of software tools, the geothermal bundle. It’s intended specifically for the detailed analysis and design optimization of geothermal ground-source heat exchanger systems.
The geothermal bundle is comprised of both the IES VE and Gaia Geothermal Ground Loop Design (GLD) software suite. The bundle enables geothermal HVAC designers/engineers to first calculate hourly load data using the Apache whole-building dynamic thermal engine built into the VE.
Designers can then import the hourly loads data into the GLD software to select geothermal heat pumps, determine the appropriate lengths of bore/pipe required for vertical, horizontal, surface water, and hybrid heat exchangers, optimize the piping layout to minimize circulation pump requirements, and calculate the annual and lifetime energy/operating/emissions costs associated with the design.
“Gaia Geothermal’s Ground Loop Design software package is the leading software suite for designing geothermal heat pump and ground heat exchanger systems,” said McLean. “GLD has been used to design many thousands of geothermal systems, including the world’s largest geothermal well fields. In conjunction with our family of software offerings, this geothermal bundle allows customers in North America to fully leverage the sustainable design opportunities of this low-carbon technology.”
“Geothermal system designs are very sensitive to load profiles. When building loads are oversized, for example, geothermal installations become excessively expensive,” said Daniel Bernstein, president of Gaia Geothermal. “This bundle provides integrated and iterative design optimization control and will enable engineers to design confident, highly cost-effective and high-performing systems. I have little doubt that this bundle will enhance the growth rate for commercial geothermal systems in North America and beyond.”
For more information, visit www.iesve.com.
Publication date: 03/22/2010