Modernizing for Comfort and Sustainability: HVAC and Plumbing Renovation at the Colorado Annex Building
The State of Colorado Annex Building at 1313 Sherman Street has undergone a transformative renovation aimed at improving comfort, efficiency, and sustainability, thanks to the RATIO design team. This project focused on breathing new life into a historic structure, replacing outdated plumbing systems and modernizing HVAC infrastructure to meet today’s performance and environmental standards. Challenges of an Aging Infrastructure The Annex Building’s original design prioritized heating and ventilation, with cooling added later as an afterthought. This retrofit approach left the building with undersized ductwork and minimal ceiling space, creating significant design hurdles. Existing ducts embedded in floors had to be abandoned in place, and engineers faced the complex task of separating basement systems (serving 24/7 State Patrol operations) from the rest of the building while maintaining both the historic fabric as well as the integrity of existing fire ratings at every level. Another major challenge was decoupling domestic hot water from the existing steam system, which remained operational during and after construction to serve adjacent buildings sharing the existing distribution system. Moving water out of the basement and into upper floors required innovative solutions to overcome spatial and logistical constraints. Electrification and Sustainability Goals Central to the renovation is the commitment to sustainability. The project targets LEED Gold certification, emphasizing energy performance, water use reduction, and refrigerant management. Electrification of HVAC systems plays a pivotal role, aligning with Colorado’s broader environmental objectives. Several system options were evaluated, including: Variable Refrigerant Flow (VRF) Chilled Water/Hydronic Heat Variable Air Volume (VAV) Packaged Heat Pump RTUs Each option offered unique benefits and limitations. While heat pumps and energy recovery systems are essential for achieving LEED points, they introduce complexities in refrigerant management. VRF systems, for example, use significant volumes of refrigerant, making enhanced credits for low Global Warming Potential (GWP) refrigerants challenging with current technology. Balancing Performance and Practicality Budget constraints, operations and maintenance (O&M) staffing, and technology confidence were key factors influencing system selection. Electrification, while environmentally advantageous, can complicate energy performance scoring compared to traditional gas systems. High-efficiency heat pumps and advanced controls were necessary to bridge this gap. Maintenance considerations also shaped design decisions. Multiple system components increase potential failure points and require ongoing investment in replacement parts. Additionally, complex control sequences demand thorough training for maintenance staff to ensure reliable operation. Ultimately, based on these factors of first cost, energy efficiency, operability, and particularly constructability, the State chose to move forward with a VRF heat pump system with integral heat recovery. This all-electric system is highly efficient, as it allows the system to move heat internally from one zone to another, utilizing the heat energy already in the building as much as possible and minimizing how much the outdoor heat pump must work to draw heat from the ambient outside air for space heating or reject heat from the building to the outside for space cooling. Ventilation was provided by a packaged heat pump Dedicated Outdoor Air System (DOAS) with energy recovery. This DOAS provide fresh, filtered outside air to the entire building, simultaneously controlling building pressure to mitigate unwanted infiltration via exhaust air drawn from each level—and all while utilizing an energy recovery wheel to reduce the load on the heat pump heating/cooling system! Plumbing Design Innovations On the plumbing side, the renovation prioritizes water conservation and metering to support LEED goals. Strategies include reducing water use and implementing additional metering for better resource management. These upgrades not only enhance sustainability but also improve long-term operational efficiency. Looking Ahead The Annex Building renovation exemplifies the intersection of historic preservation and modern engineering. By addressing spatial limitations, embracing electrification, and pursuing LEED Gold certification, Colorado is setting a benchmark for sustainable government facilities. This project demonstrates that even the most challenging infrastructure can be transformed into a model of efficiency and environmental stewardship. Photography © Frank Ooms
Sustainability Meets a New Era of Learning: Back to School at DPS RASA
Denver Public Schools (DPS) set a new standard with the Responsive Arts & STEAM Academy (RASA), a ground-up, 120,000-square-foot school designed and built in two phases. Phase 1 opened in August 2024 for ECE through 5th grade, followed by Phase 2 in August 2025, expanding the school through 8th grade. From the start, the project team planned ahead—accounting for future mechanical loads, water heater capacity, and even sanitary sewer piping depth—ensuring a seamless expansion. DLR Group led the architectural design, with 360 Engineering providing mechanical and plumbing engineering and consulting expertise. Energy Modeling and Mechanical Systems The design team was challenged to create a highly energy-efficient building. Energy modeling was used to evaluate three mechanical system options: Packaged Heat Pump Roof Top Units (RTUs) with downstream Variable Air Volume (VAV) boxes with electric zone heating A geothermal heat pump system Chilled beam cooling with radiant heating flooring With 360 Engineering’s input and guidance, the team compared installation cost, energy efficiency (measured in Energy Use Intensity, or EUI, given as a measure of energy use per square foot per year), maintenance needs, and long-term operating costs. The VAV RTU system emerged as the best fit—offering strong efficiency, the lowest upfront cost, and familiarity for DPS’s facilities staff. The system incorporates air-side economizers and energy recovery wheels to improve performance further, taking advantage of Colorado’s dry climate. Smart controls also monitor CO₂ levels in each space, adjusting outdoor air intake to strike the right balance between energy savings—less outdoor air to heat or cool—and indoor air quality, ensuring efficient operation while keeping classrooms filled with fresh air to support active, engaged learning. All Electric Designed with the future in mind, RASA is the district’s first all-electric school: heat pump technology powers the mechanical systems, domestic water heating is electric, and even the kitchen ranges and ovens are induction. Now, more than a year after RASA’s grand opening, with the Phase 2 expansion substantially complete, early performance data is beginning to prove the success of the design and construction efforts. While initial energy use reflects commissioning, ongoing construction, and partial occupancy, adjusted metrics show the building’s EUI in the low 30s—right on target with original energy modeling and well below Denver’s K–12 benchmark of 48.1. RASA stands as a safe, energy-efficient learning environment, ready to support and inspire the next generation. Contact us today to discover how an all-electric design can power your next project. E-mail Stacey Richardson at srichardson@360eng.com to learn more.
Innovating the Future: NREL’s New State-of-the-Art Control Facility at the Flatirons Campus
The National Renewable Energy Laboratory (NREL) is a leading research facility on clean energy and alternative fuel sources. This year, the Flatirons Campus and Wind Facility are completing their first ground-up building construction in several years, led by the HDR team. The new state-of-the-art building will act as the central control facility for all research efforts on the Flatirons Campus. Modernized building construction requires a modernized mechanical and plumbing system to complement the building design. During the early phases of design, five (5) different mechanical systems were considered, with a wide range of factors including ease of maintenance, energy efficiency, and utilization of heating and cooling utilities. Ultimately, after energy modeling, lead time considerations, and cost considerations, NREL opted to proceed with the first Variable Refrigerant Flow (VRF) mechanical system on their Flatirons Campus. The VRF system includes a packaged heat pump Dedicated Outdoor Air Unit (DOAS) with a heat recovery wheel for low-energy preconditioning of the building. The DOAS provides ventilation air to each indoor fan coil unit, easily complying with code requirements for the varied room types within the building. The building hosts conference spaces, electronics labs, a data center, and general office space. The control facility was optimized to maximize floor space, presenting the unique challenges of configuring mechanical and plumbing systems in the limited plenum space. The team utilized REVIT during design to model systems beyond the 2D of CAD and capture any constructability conflicts early on. The building is nearing the end of construction and the final stages of mechanical commissioning, with an occupancy slated for April. The unique mechanical and plumbing integration of exposed versus concealed aspects balances with the architectural aesthetics to create a truly beautiful building that is both pretty to look at and functions as a high-tech research facility. It’s great when these two design objectives find a way to cooperate!
NPS Ozark Big Spring – Mechanical Coordination in Tight Spaces
The National Park Service was looking to renovate its existing Lodge building and cabins at the Ozark National Scenic Riverway Big Spring site in Missouri. The site includes thirteen (13) rentable cabin buildings, a concessioner’s house, a laundry building, a museum building, and the riverfront lodge. The area had experienced historical flooding in 2015 where the lodge itself was in 10’ of water on the main level photographed above. This flooding closed the park site, and all the buildings sat dormant until this project was initiated. The lodge experienced the worst damage, and all systems required full replacement. The other buildings onsite were lucky to be higher on the hillside and were not flooded. The lodge building provides spaces for park users and guests to congregate and eat meals and serves as a launch point on the river, where there is newly built dock access. This lodge is also outfitted with a commercial kitchen for the concessioner to provide meals for the guests. Close Coordination & Minimizing Mechanical Space Needs Missouri experiences high humidity, so the mechanical systems were designed with full dehumidification in mind. The existing systems serving the lodge were non-existent; there was no heating or cooling serving the building previously. This required new mechanical space to be created outside to account for these cooling and heating needs. These new outdoor systems serving the lodge are two heat pump condensing units and a makeup air unit for the kitchen. Makeup Air Unit at the Kitchen The makeup air unit was a tight fit, but we were able to work with the existing area on the side of the lodge. The two new heat pump condensing units, however, were going to require a new mechanical yard to be formed. This lodge is a historical structure, so everything needs to be done to maintain the current aesthetics. We took extensive care to minimize the mechanical yard footprint and position it to hide mechanical equipment from the general public’s view. Mechanical Yard Behind the Lodge Ultimately, the mechanical space created was the ideal size and location to leave the least impact on the site while still providing complete heating, cooling, and dehumidification to what was formerly a hot, cold, and stuffy building. Air Handling Units Above the Ceiling We had new heat pump air handling units installed above the ceiling inside the building. These units were about as large as you could fit within these existing ceiling cavities, but through close coordination with our structural engineer and architect, we developed solutions to make these units semi-removable for ease of replacement at the end of their life and provide ideal access for ease of serviceability during their operational lifespan.
Sustainability Meets a New Era of Learning: Welcome to DPS RASA
New School Year, New School Denver Public Schools (DPS) pushed the design envelope with this over 60,000-square-foot ground-up new school. The current design houses grades ECE through 5th grade with a future Phase 2 expansion to bring it up through 8th grade and just shy of 80,000 square feet. Phase 1 was designed with Phase 2 in mind, from mechanical loads and water heater capacity down to sanitary sewer piping depth. As the architect, DLR Group led the design team in which 360 Engineering provided mechanical and plumbing engineering and consulting. Responsive Arts & STEAM Academy FNE (RASA) hosted its ribbon-cutting ceremony on Friday, August 2, 2024, just in time for the new school year! The RASA approach is built on a culturally sustaining, community-responsive foundation that respects all learners. It aims to foster a lifelong love of learning through creative and critical thinking, project-based learning, and the discovery of students’ talents. The model emphasizes the Arts as essential to learning, integrating them across subjects to promote higher-order thinking. Historically, students in Far Northeast Denver have lacked access to robust arts education, but RASA seeks to change this by valuing emotional education alongside logic and reasoning, creating a more holistic human experience. Energy Modeling and Mechanical Systems The design team was tasked with designing a highly energy-efficient building. Energy modeling was used to compare three mechanical systems: Each system has pros and cons, which were discussed in detail with 360’s input and guidance. The biggest decision points were identified as installation cost, energy efficiency (measured in Energy Use Intensity or EUI, given as a measure of energy use per square foot per year), maintenance requirements, and operational costs. The VAV RTU system was chosen as it provided the best efficiency with the lowest installation cost and a familiar system for the District’s facilities maintenance team to work with. This system also included air-side economizers and energy recovery wheels to further increase efficiency and make use of the dry Colorado air. Additionally, the controls systems monitor CO2 levels in the various spaces and modulate the outdoor air intakes to provide the right amount of ventilation (known as Demand Control Ventilation), providing the right balance between energy savings—less outdoor air to heat or cool—and indoor air quality, keeping CO2 levels down and enough fresh air coming in to keep learning minds active and alert! All Electric With RASA’s successful grand opening, the design team immediately began designing the Phase 2 expansion. We are excited to see the school we have designed realize its potential as a safe, energy-efficient facility that will foster growth in the next generation. With a mindset for the future, the school was designed to be all-electric: the mechanical system is powered using heat pump technology, domestic water heating is electric, and all kitchen appliances are electric—even the ranges and ovens are induction-type! This is the District’s first all-electric school.
Commissioning in the Hottest Place on Earth!
Our projects with the National Park Service take us to some pretty cool places…this is not one of them. Death Valley National Park (DEVA) holds the record for the highest recorded temperature on the face of our planet, at over 130°F! As you might imagine, it takes a lot to keep buildings comfortable in a climate like that. 360 is currently wrapping up a project in DEVA, specifically at Scotty’s Castle, where the design team replaced an outdated water source heat pump system with a full water-cooled chiller plant and hydronic boiler system. The team utilized a former stable building as a mechanical room to house boilers and chillers and routed buried piping hundreds of yards to the castle itself in tunnels built by Scotty nearly 100 years ago. The system utilizes a closed-loop cooling tower to minimize water loss while still taking advantage of the dry air’s low wet bulb temperature to reject heat from inside the castle to the ambient air far away from the building. All in all, a well-thought-out and resilient system that will provide effective and reliable cooling and heating (it does get cold in Death Valley sometimes!) for years to come, making the visitor (and Park staff) experience more enjoyable and sustainable. But the best system design can be crippled if the systems are not properly started up, tested, and deficiencies corrected before the building occupants move in—in other words, commissioning! The certified Commissioning Authorities (CxAs) at both 3601 and AE Design teamed up to visit the site, observe the system installations, and put the equipment through its paces to make sure everything is installed and operating as intended by the design team. The commissioning process began with a review of the construction documents as well as equipment submittals in order to familiarize ourselves with the systems being installed and the design intent for their function and operation. From there, we developed both pre-functional checklists (PFCs) and functional performance test protocols (FPTs). The PFCs are filled out by the installing contractor and serve as a quality control and assurance check to ensure systems have been provided and built with all necessary components for operation and are ready to be tested against the design intent and sequences of operation. Once the contractor confirms systems are ready for functional testing via the PFCs, the commissioning (Cx) team books a flight and heads to the site for testing. We check every system visually to confirm that systems and equipment match what was submitted and approved by the design team and that installed layouts match the design intent in the construction documents. We then work with the mechanical and controls contractors to test the systems using the FPT protocols previously developed. These tests include various modes of operation, such as typical occupied/unoccupied operations, generating false heating/cooling loads to make sure the boilers, chillers, various pumps, and valves all react as intended, and even simulating failure modes to make sure that redundant systems come online when needed and equipment is properly protected in the event of a real equipment or system failure in the future. The Cx team documents the installed conditions and the results of the various tests and provides a log of deficiencies to be addressed before final handover of the project to the owner. As needed, the Cx team makes additional site visits to follow up on deficiencies and make sure all systems have been observed as fully operational before issuing the final Commissioning Report. Commissioning is a vital process, particularly for complex projects and systems. The fact that our team made several trips to the site in order to complete all the testing and re-testing of systems to ensure everything is operating per the design intent and owner’s project requirements illustrates two key concepts. First, that commissioning is critical for the success of a project, as the list of deficiencies and the need for multiple trips to close out those issues clearly shows—rarely is everything installed and operating 100% correctly the first time it’s put to the test! Second, 360 and AE Design are committed to ensuring that the systems turned over to the owner are fully functional and will serve the building occupants well for years to come. It helps that we get to visit some pretty cool places—even if they’re actually rather hot! Interested in learning more about Scotty’s Castle? You should be! Check out the links below.2,3 1Wondering how 360 can be the designer and the CxA at the same time? We maintain objectivity by keeping the CxA completely uninvolved with the design team throughout the design process. Our CxAs work for the owner, either contracted directly or under the general contractor and are accountable to only them. While we obviously work together with the design team through the commissioning process, our CxAs always pursue the goal of helping the whole team achieve the owner’s project requirements and are not afraid to challenge the contractor or the design team when needed to attain that goal. 2https://www.nps.gov/deva/learn/historyculture/building-scottys-castle.htm 3https://www.dvconservancy.org/scottys-castle/
Gunnison County Library – The Road to Net Zero
Gunnison County Libraries was looking to replace its existing library in Gunnison, Colorado, with a new sustainable building providing flexible and functional community space. The 15,000-square-foot public facility also needed to stand up to the harsh and variable weather conditions experienced in Gunnison. The high-elevation mountain sun is intense all year round, while winter ambient temperatures in the Gunnison Valley can drop below negative 30 degrees. In addition to cold temps, deep and heavy snow is common, so careful design of the roof systems by the Anderson Hallas Architects team was critical to handling snow and ice. Energy Modeling and Assistance in Achieving Sustainability Goals 360 Engineering provided mechanical and plumbing engineering services, including energy modeling and assistance in achieving sustainability goals for the project. The design team was tasked with providing a building with an EUI (Energy Use Intensity) under 30. As a reference, the median EUI for a library in the US is 71.6 (Energy Star Benchmarking). The energy-efficient mechanical system combined geothermal ground source heat pumps and a variable air volume dedicated outside air system (VAV DOAS) with new DDC controls. The energy model completed at the end of the design predicted an EUI of 27. Building EUI (Energy Use Intensity) goals for Net Zero What does a low EUI have to do with Net Zero? A chart was developed by Building Green (BuildingGreen.com) to provide EUI goals for buildings that, combined with a solar PV array, provide a pathway to a Net Zero building. The Gunnison Library, a single-story, 15,000-square-foot building, has a targeted EUI of over 50. However, the chart developed by Building Green is based on a building using 70% electric and 30% natural gas. Having a goal of reducing fossil fuels and a fully electrified building shifts this chart, and the design goal of under 30 EUI puts us on the right track to achieve Net Zero. Utilizing Solar The Gunnison Library utilizes an 18kW solar array with the intent that solar PV could be expanded as the allowable kW per array increases. The 18kW array provides 1.2 watts per square foot and is a minimal array, considering the average size of residential arrays are 7.1 kW (NREL). So, how is the building doing? Over the last five months, the building has been operating with an EUI of 15.5! As mechanical engineers, this isn’t just a triumph; it’s a testament to our role in shaping a future where Net Zero isn’t a lofty ideal but a measurable reality. It’s a call to action for mechanical engineers everywhere—to engineer not just systems but sustainable solutions that propel us toward a future where our buildings don’t just weather the storm but become beacons of environmental responsibility.
The Power of Electrification in Preservation: NPS Fort Vancouver Museum Facility
Background: The National Park Service (NPS) stores, maintains, and displays historic collections, artifacts, and culturally significant pieces across various sites. Recognizing the need for efficient infrastructure, NPS seized the opportunity to relocate collections and archives from several sites in the Northwest Region into one larger facility at Fort Vancouver National Historic Site in Washington. Key Objectives: Site Selection: NPS chose Fort Vancouver Building 405 as the repository for collections from four national parks, totaling over 3 million items. Fort Vancouver Building 405 Rehabilitation Project Facility Overview: Public Engagement Spaces: Mechanical System Options by 360 Engineering Discovery and Presentation on Anderson Hallas Architect’s Team: Variable Refrigerant Flow (VRF) System Selected: Advantages of VRF System: Conclusion Adopting the Variable Refrigerant Flow (VRF) system for Fort Vancouver marks a significant step in realizing NPS’ Service-Wide Curation Facility Plan. This decision ensures optimal preservation conditions for the extensive collection while promoting energy efficiency in line with NPS’ principles. Ready to upgrade your building or project with electrification? Let’s discuss your Mechanical Engineering needs today. Contact us to book a 30-minute consultation.
Optimized Cooling Tower Design for Increased Performance and Efficiency
At 360 Engineering, we consistently optimize projects by creating custom designs and recommendations. This project we started in 2018 for the National Renewable Energy Laboratory (NREL) was no exception. Once COVID-19 hit, we learned how the economy could quickly derail a project, but we steered it on the right track by helping NREL find a viable path forward and breaking the project into two phases. NREL realized one of its cooling towers at the Solar Energy Research Facility (SERF) was using a significant amount of water, and they brought our team in to find a solution. During a gas line replacement project, water was encountered immediately below the access road, and it was determined to be a leak of the condenser water lines from the cooling towers to the chilled water plant. “360 Engineering reconfigured the operation of the cooling tower condenser water plant to optimize both the performance of the plant as well as increase the system redundancy moving forward.” This project included our long-time electrical engineering partner, AE Design, and structural and civil engineers from Martin/Martin. We have an amazing team of expert consultants who have worked with us on NREL projects since the beginning. For any questions, inquiries, or to get started on your next project, Contact Us.
Designing for Sustainability in Extreme Climates
Here are some considerations for designing mechanical systems for properties in remote/climate-sensitive locations, meanwhile achieving the energy savings needed to accommodate sustainability goals, such as in our Gunnison County Library project. • Utilizing a geothermal system allows for an all-electric system without having to deal with the extreme low temperatures as a source for heat-pump heat. • Energy modeling is critical when designing a geothermal system not only to size the bore field but to ensure that the heating and cooling loads are sufficiently balanced to mitigate long-term ground temperature drift. • In environments such as this with year-round intense sun and heating dominant loads, exploring different glazing locations and characteristics is important as sometimes glass that allows more solar load in, while increasing the cooling load, will decrease the heating load, and may increase the overall efficiency of the building. • Incorporating energy recovery for ventilation is key in mitigating the energy associated with bringing in fresh air during very cold temperatures, especially when utilizing an all-electric system. Read more about the integrated design team approach here: Colorado-Real-Estate-Journal_330353 (windows.net)