The Power of Small + Simple: Achieving Big Impacts for Net-Zero Projects

At the AIA Colorado Practice + Design Conference, the session “The Power of Small + Simple: Achieving Big Impacts for Net-Zero Projects,” presented by Tom Hootman, AIA, Scott Bishop, Assoc. AIA, and Saeed Amirchaghmaghi, explored the Smith Road Office Building as a replicable model for achieving Net Zero energy in small-scale architecture. This 5,000-square-foot pilot project, completed in 2024 for Denver Parks and Recreation, demonstrated how intentional design can meet ambitious sustainability goals. Studio Completiva is the architect of record and Form & Flow the building performance consultant.

Guided by the City of Denver’s Net Zero energy definition, the project prioritized energy efficiency, all-electric systems, and renewable energy integration. The team employed an integrated design process and a passive-first approach, focusing on climate-responsive orientation, robust thermal envelopes, and energy-efficient materials. Tools like Ladybug Tools and Autodesk Forma supported performance modeling, while energy targets were set based on roof PV capacity.

Construction challenges, including a mineral wool shortage, led to material substitutions like Tyvek weather barriers and foam insulation. Cascadia clips reduced thermal bridging, while passive strategies such as solar heating, cross-ventilation, and thermal mass enhanced energy efficiency. The building achieved 94% spatial daylight autonomy, supported by operable windows, low-power lighting systems, and simple, cost-effective interiors.

The mechanical systems featured a geothermal array with seven boreholes, dedicated outdoor air systems (DOAS), and energy recovery ventilation (ERV) for improved air quality. Lifecycle cost analysis revealed geothermal as the most cost-effective option, aligning with Denver Parks and Rec’s long-term goals. Embodied carbon reduction was achieved through wood construction, recycled cladding, and low VOC materials.

Energy model results showed the building’s performance closely matched predictions, with PV panels set to achieve net-positive energy generation. Maintenance feedback indicated successful operation, supported by the Egauge dashboard for real-time monitoring. The project served as a prototype for Denver Parks and Recreation, inspiring future Net Zero designs for larger facilities like recreation centers.

This session underscored the replicability of these strategies, offering architects a practical toolkit for achieving sustainability in small-scale projects. By leveraging integrated design, passive-first principles, and innovative systems, the Smith Road Office Building exemplifies how thoughtful architecture can drive impactful climate action.

Use Performance Modeling for Early Design Decisions

Tools like Ladybug in Grasshopper enable rapid evaluation of passive strategies without full energy modeling. This allows architects to test solar gains, shading effectiveness, and thermal performance during schematic design when changes are still cost-effective.

Doing a full energy model is too time consuming. It takes too long. And looking at the EUI of like, subtleties of like the how much overhang do you have really? Is too much noise, you want to dial into what. What are you impacting? So in this case, it’s very literal. This is the summer months. Anytime the temperature is over to 75 degrees, we know the exact solar radiation amount hitting the each of those penetrations.

Passive Design Over Active Systems

Investing in passive strategies like climate-responsive orientation, high-performance envelopes, and building science fundamentals creates a foundation that reduces mechanical system requirements and provides long-term value throughout the building’s life.

Passive design, climate responsive design, orienting your building, those simple things that we should be doing, that sometimes we’re not. But also paying attention to building science… all that really trumps the active systems, right? But it also sets the stage for really different active systems and smaller active systems.

Wood Framing Doubles Thermal Performance

Switching from steel to wood framing eliminates thermal bridging and can double the effective R-value of wall assemblies while often reducing costs. This simple change provides significant energy and embodied carbon benefits for small commercial buildings.

When you put R19, R21 in a cavity, you’re not getting an R21 wall. But you might be getting an R7 wall with steel thermal bridge, the conductivity of steel. So you’re not getting a lot of value for that. We use wood… we could actually save money by going wood, why not? And of course we get an embodied carbon benefit… But we also double our value in that cavity.

Lifecycle Analysis Drives System Selection

Evaluating mechanical systems through 25-year lifecycle costs including maintenance, not just first cost, often reveals that higher-performance systems like geothermal provide better long-term value, especially when combined with PV.

We got some first cost estimates from our cost estimator and we estimated some maintenance costs with a mechanical engineer over a 25-year period and did a lifecycle analysis… It turned out you have the lowest cost is just a very inexpensive air source heat pump… The second lowest cost was the geothermal with PV.

Simple Finishes Enable Performance Investments

Choosing simple, elegant interior finishes like polished concrete floors and exposed ceilings frees up budget for high-performance envelope and systems while providing thermal mass and celebrating structural elements.

There are no fancy finishes. Not having that many fancy finishes helped us to compensate for having bigger windows or having a more robust HVAC system. But even with those simple finishes, we were able to achieve a lot because when we have that concrete floor, its actually polished, so it brings the daylight in, but it also acts as a thermal mass.

Interior Air Sealing Outperforms Exterior Barriers

Atomized acrylic sealant applied from the interior can achieve better air barrier performance than traditional exterior methods like Tyvek, often at no additional cost while providing measurable results through blower door testing.

Studio Completiva had recent success using a atomized acrylic sealant. So they spray it from the interior… our target was 0.2. So that’s a CFM per square foot of envelope at 75 pa of pressure… we actually were able to hit 0.15. We were able to get it even a bit better. That was a nice move. And there was no cost change to do that.

Shoebox Massing Simplifies Thermal Control

Simple rectangular building forms make it easier to create continuous thermal envelopes and control heat loss. Complex geometries create more opportunities for thermal bridging and air leakage, increasing both energy use and construction costs.

What is a shoebox mass? It’s essentially a simplified version of your building… with a simple rectangle, simple mass, and want to emphasize that it makes it easier to control your thermal envelope. With a passive first approach, you want to wrap your building like you would a jacket.

Post-Occupancy Monitoring Validates Performance

Installing simple, cost-effective energy monitoring systems like eGauge enables real-time performance tracking and validates energy models. The Smith Road building performed within 12% of predicted energy use in its first year.

Within the zero energy project, it doesn’t end with design, it has to be operated as one. So they need to be paying attention to energy and having a simple dashboard… This is actually another Colorado product called eGauge that I particularly like because it’s so simple and it’s really cost effective, especially in small building.

High-Performance Windows Enable Passive Strategies

Investing in windows that exceed code requirements (U-0.14 vs code baseline) with non-conductive frames enables effective passive solar heating in winter while maintaining comfort, supporting natural ventilation strategies year-round.

Exterior windows have a U value of 0.14 and solar heat gain coefficient of 0.28, which is way better than the code. It actually meets the passive house prescriptive requirement… if you go with like uPVC in this case or fiberglass, you reduce that thermal bridging.

Material Choices Reduce Embodied Carbon

Simple material substitutions like calcium silicate masonry instead of CMU, recycled plastic composite cladding, and wood framing can significantly reduce embodied carbon without complex lifecycle assessments or major cost impacts.

So that wasn’t necessarily in our scope of work. It was a zero energy building. We didn’t do a whole building life cycle assessment. We didn’t invest in that. But we made decisions based on embodied carbon throughout the whole project. And it’s really not that hard. There are Environmental Product Declarations on everything. We use DC3, easy tool to compare and find products.