Offices change to accommodate sustainability goals
To appeal to various clients and work styles, office buildings are moving toward becoming more energy efficient
Office building insights
- Office building design is moving toward becoming more energy efficient.
- Building owners are demanding more net zero options in their office buildings, such as electric vehicle charging stations.
- Miles Brugh, PE, Project Electrical Engineer/Manager, ESD, Chicago
- Adrian Gray, C Eng, Eur Ing, Global Director – Commercial and Real Estate Sector, HDR, London
- Matt Humphries, Associate Principal, Arup, Toronto
- John Yoon, PE, LEED AP, Principal Engineer, McGuire Engineers Inc., Chicago
Describe a project in which electric vehicle charging stations were included. What were the challenges and solutions on this project?
Miles Brugh: Electric vehicle charging has come on like a storm in the industry. Specifically in the city of Chicago, officials have passed an ordinance that requires all new commercial projects to provide capacity for 20% of all parking spots to be EV-ready. Our designs factors in this additional capacity. We have also been seeing an increase of Day One installed from two to four chargers, currently growing to up to 10% of the total parking spots.
Adrian Gray: We have delivered charging stations across the U.S. and also around the globe. EV charging presents an operational challenge in that the demand schedules tend to be unknown in that they can vary from hour-to-hour. When combined with client-specific utility electric rate schedules that offer time-of-use incentives or demand-based charging, this EV charging inconsistency can sometimes do more financial harm than good with these specific types of utility structures. The solution is to work with the electric utility company to allocate the EV charging to a separate building meter with its own rate structure and keep the building loads on the rate structures that can benefit from demand-reduction based measures.
John Yoon: We are often asked to perform feasibility studies or integrate level 2 EV service equipment (EVSE) into our projects. While it isn’t much of a challenge to have a small number of them, we’re seeing requests to accommodate dramatically increased EVSE quantities.
For example, Chicago has a parking zoning ordinance for new construction that mandates that associated parking areas be EVSE-ready. In general, anywhere from 1.33 to 2 parking spaces per 1,000 square feet of building area are required overall for business occupancies. Chicago’s ordinance requires 20% of that total quantity of spaces be EVSE-ready. Assuming 6.6 kW per EVSE, the power required by those EVSE is starting to approach what we reserve for lighting and receptacle usages in the office areas. While we can accommodate that in new construction, that is seldom the case in existing buildings. When those buildings were originally constructed, no one had any indication that this type of electrical load would need to be accommodated.
The preliminary drafts of the 2024 IECC would seem to indicate that there is a good chance that EVSE requirements will be incorporated into that code. This is a game changer and will dramatically change how we design electrical distribution systems. Load management systems to allow multiple chargers to share a limited source of power seems like the obvious solution to capacity issues.
However, the American EV market is moving faster than codes and standards development. Without universally mandated standards, vendors have little motivation for standardization and as a result, most available load management solutions are proprietary. However, this might change with requirements associated with EV charger infrastructure funds that were earmarked in federal government’s Inflation Reduction Act.
What unusual systems or features are owners requesting to make their office facilities more efficient?
Adrian Gray: Not necessarily an unusual system or feature, but more and more we are seeing building owners want more granular validation that their building operation is efficient and performing as per the design intent. At HDR we find that this is most successfully achieved via a cloud-based or locally hosted fault detection and diagnostics (FDD) platform that collects interval data from the building automation system to seek out energy-related anomalies that impact building performance. FDD identifies sensors that have deteriorated or are drifting, sequence of operations that are not operating as intended, irregular equipment efficiencies and occupancy-based optimization recommendations.
Matt Humphries: There’s a focus on carbon. There’s a real appreciation for looking at the long-term operational carbon and energy use in buildings. What is the carbon cost of construction? How much embodied carbon is there in the building at the outset, not including future ongoing energy use? Arup is at the forefront of appreciating the life cycle carbon impact of construction. A key developing trend is to look at the carbon content of mechanical systems, in terms of both embodied and operational carbon.
John Yoon: Again, upcoming building performance standards and decarbonization efforts are an overriding concern. Specify thresholds for building energy use intensity will naturally force us into more efficient systems and equipment selection. It isn’t going to be an owner’s request — it will be a requirement.
What types of sustainable features or concerns might you encounter for office buildings that you wouldn’t on other projects?
Adrian Gray: One sustainable concern for office buildings that might be encountered is buildings that do not have a robust tenant- and/or sub-metering configuration, thus resulting in tenants not being able to know their true energy consumption footprint for their leased space. This leads to the notion that any efficiency improvements that are undertaken in the space will not result in any tangible savings as these most likely have a per-square foot building utility charge arrangement.
Matt Humphries: Microgrids are the future. Understanding how energy is being used and modulating peaks and valleys offers opportunities to save carbon and money. This is a key reason we use digital twins to design the infrastructure for electrical network systems: we can regulate or optimize with a digital twin and it’s an opportunity to have impactful changes toward greater sustainability.
What types of renewable or alternative energy systems have you recently specified to provide power? This may include photovoltaics, wind turbines, etc. Describe the challenges and solutions.
Miles Brugh: We have specifically been working with clients to provide either on-site solar or use a power purchase agreement to buy renewable energy from the grid. We have started to see more studies on existing facilities to implement different solar PV approaches to provide the most output. Some of these approaches have been roof-mounted on the building itself, solar car ports in large parking areas and ground mounted systems on surrounding land.
Adrian Gray: HDR is investing in the research and development to better prepare for how green hydrogen will change the building energy sector. HDR has developed internal toolsets that analyze the consumption, footprints and costs of various configurations of green hydrogen systems consisting of solar photovoltaics to generate on-site electricity that powers electrolysis units to generate atmospheric hydrogen, gas compressors to store hydrogen on-site at varying pressures and hydrogen fuel cells to fulfil the real-time power draw needs of various building types. For zero energy buildings, on-site compressed hydrogen offers many benefits over traditional battery-based storage systems, primarily the optimization volumetric energy density.
John Yoon: Our regional energy costs are well below the national average. As such, distributed energy resources solutions haven’t been cost effective. However, electrification and electric vehicle adoption are game changers. Forthcoming building performance standards recognize this potential increase in electrical utility grid demand and as such, some type of ‘solar ready’ and energy storage system provisions should be part of any comprehensive BPS.
What are some of the challenges or issues when designing for water use in such facilities?
Adrian Gray: To validate that a particular design is a low water usage building, design teams should really focus on the building’s HVAC system type, specifically if it is a water-cooled system or not. Cooling towers consume water via windage losses, blowdown and evaporation, with the latter evaporation (the physics behind cooling towers) accounting for 66% of cooling tower water usage. As building designs transition to fully electrified, the designs also need to transition to low-to-no HVAC water consumption systems in parallel. Solutions such as heat recovery chillers and geo-exchange ground-source systems need to be discussed and analyzed starting on Day One.
John Yoon: Instantaneous water heaters, while efficient, don’t play nice with low flow plumbing fixtures. The turn on flow requirements for those types of heaters is often more than what the fixture is rated for. This often means resorting to smaller tank type heaters.
How has the demand for energy recovery technology influenced the design for these kinds of projects?
John Yoon: Again, energy code requirements have driven specification of energy recovery systems and similar technologies more than anything else. Energy recovery ventilation systems have been mandated for system that exceed certain outside air percentage thresholds for several code revision cycles.
Adrian Gray: As building designs transition to more and more fully electrified building designs, we see the central component of such buildings to be the heat recovery/reclaim chiller. This technology allows heat to be recovered from the cooling generation process and at significantly elevated efficiency levels as this heat would typically be expelled into the atmosphere via air-cooled or water-source cooling systems. This form of recovery allows a building to satisfy its first stage cooling and first stage heating in a fully electrified plant design without the concern of ambient temperature thresholds as such a system is isolated from outside air conditions.
High-performance design strategies have been shown to have an impact on the performance of the building and its occupants. What value-add items are you adding these kinds of facilities to make the buildings perform at a higher and more efficient level?
Adrian Gray: The façade design can have a significant impact on building efficiency while also contributing greatly to occupant performance. Natural daylighting and access to views are crucial to occupant performance and the thermal performance of the building facade/envelope does not have to be the weak point to achieve such occupant-focused amenities. Using simulation-based analysis to determine the proper combination of vision glazing, exterior/interior shading, interior thermal mass materials and overall assembly thermal performance values will assure that both that heat loss is minimal when not required, passive heating is optimized when needed and that occupants are comfortable.
Optimization of the building envelope can lead to the tipping points phenomenon, in that a properly design facade from a heat gain/loss perspective can lead to more efficiently sized thermal equipment, comfort delivery systems and ultimately smaller plant generation equipment, thus optimizing the building’s performance.
Matt Humphries: The focus is on energy efficiency. As much as possible, no combustion takes place within building and everything is electrified. A ground source system stores rejected heat from summer and reuses heat in winter. We added an energy recovery system to enable energy recovery from waste air streams. Since it’s a lab building, there is a lot of exhaust air from fume hoods and we were able to develop integrated approaches to energy recovery. Arup was the sustainable design consultant and energy modeler.
The university’s target was 20% better than ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings in base design and they were looking for a 15-year payback for investments that could take the building to 40% better. We wanted to look at 40% better than ASHRAE 90.1. By modulating the fume hoods based on the types of pollutants involved and incorporating a geo exchange, we ended up with a 63% better design, 60% in fact after modifications were made during construction.
It’s one of the most energy efficient lab buildings and it includes office space for researchers and grad students and as I outlined the air quality is excellent in both the labs and the offices.
What level of performance are you being asked to achieve, such as WELL Building Standards, LEED certification, net zero energy, Passive House or other guidelines? Describe a project and its goals, identifying the geographic location of the building.
Miles Brugh: We are seeing interest in WELL, net zero and other similar performance targets. Within the city of Chicago, we are working on new restaurant/tap that is targeting U.S. Green Building Council LEED gold. The primary goal with the project is that it is going with an existing building so we have to work with our LEED partners on the project to review the different systems and recognize there is limited improvements we can do to the existing facade. The project is looking to provide on-site solar as well as exploring a power purchase agreement to offset the rest of its electrical consumption. At the moment the project is on target to meet the LEED gold target.
Adrian Gray: In North America, we see LEED as the predominant third-party sustainability certification request, with various high-performance projects seeking to explore the International Living Future Institute’s zero energy and zero carbon certification programs. Elsewhere around the globe we are experiencing the Nabers system becoming more popular.
Internally, HDR looks for opportunities to take a high-performance project and develop this into a net zero energy project via a pathway to net zero analysis. The results of this internal analysis are subsequently presented to the client from a perspective of energy, carbon and cost; with the desired outcome that the majority of the explored measures can be incorporated into the project design, thus creating added value for the client.
Matt Humphries: WELL, net zero and LEED are pretty common. LEED is now being used more as a framework to evaluate needs and less as a complete process to be taken all the way to certification. Defining net zero is becoming more important. The pandemic highlighted the value of the WELL building standards, given its focus on occupant health and well-being and what impact that has.
John Yoon: Our company was engineer of record for one of the first WELL certified projects in 2016. Back then, it was expected that WELL would eventually overtake LEED, bit those predictions never came to fruition. Ultimately, the program costs and complexity killed numerous WELL certification projects. We’ve only seen a handful of WELL certification projects move forward when chief sustainability officers for anchor tenants required it from the landlord.