UW‑Madison students recommend solar plus heat‑pump package, estimate multi‑hundred‑thousand-dollar cost to cut pool and community center emissions

Students from the University of Wisconsin–Madison’s Energy and Analysis and Policy Center told the Monona Sustainability Committee on May 8 that a mix of rooftop/parking‑canopy solar and heat‑pump systems could sharply reduce emissions from the city’s pool and community center, but would require substantial upfront capital.

The students said Monona’s municipal sustainability goals—"to reach net 0 carbon emissions by 2040 and also to reduce energy by 50% also by 2040"—are more aggressive than state and utility targets and that reaching them will require both equipment upgrades and operational changes. Their analysis focused on the pool and the adjacent community center because those two facilities together account for a large share of the city’s municipal building emissions.

Their measurements and modeling showed the pool and community center produced roughly similar emissions in the most recent full‑year dataset (2023): the pool about 53% and the community center about 47% of the two‑site total. They reported 61% of the combined site emissions are from natural‑gas combustion (principally heating the pool and the community‑center building) and about 39% from electricity (largely summer cooling and pool electrical loads).

Based on four high‑level scenarios the students modeled (business‑as‑usual; solar only; solar plus ground‑source heat pump for the community center; and solar plus ground‑source heat pump for the community center plus an air‑source heat pump for the pool), they reported these outcomes for the modeled year (2023 data):

- Business as usual: about 300 metric tons CO2e at the combined site. - Solar only (rooftop + parking canopy, capital only): annual emissions drop to about 184 tCO2e (roughly a 40% reduction); reported capital cost (students’ capital‑only estimate) about $650,000. - Solar + ground‑source heat pump for community center: additional emissions reduction (student estimate) to a roughly 61% total reduction for the site; added capital roughly $600,000 (reported combined capital near $1.4 million). - Full electrification (no natural gas; ground source for building and air‑source heat pump for the pool): modelled emissions decline to near zero for site operations (students reported a 99.4% reduction for the modeled components) and an energy use reduction of about 62%; reported capital cost in the analysis about $2.5 million.

The students and their advisor emphasized the study is a feasibility exercise, not a final design: the modeling used rules of thumb and open tools rather than commercial design software, and the capital figures reported were capital‑cost estimates only and did not include ongoing maintenance, detailed financing, or full life‑cycle cost analysis. As the students explained, "we were trying to answer the question if it's feasible or not," and they recommended pursuing more detailed design and financial analysis before committing funds.

They also evaluated lower‑cost operational measures. Their operational analysis found: a modest HVAC setback (5–15% reduced HVAC during off‑peak hours) could yield a roughly 13% emissions reduction for the community center without substantially disrupting access; closing one full day each week could cut emissions by about 20% but would significantly limit public access; and trimming daily hours could yield slightly larger reductions but could affect evening usage. The students modeled remote work for eligible city hall staff and estimated that a three‑day remote schedule for eligible employees would reduce municipal emissions only modestly (they reported roughly a 3.3% reduction for the modeled staff commuting emissions), so they did not recommend pursuing remote work primarily as an emissions strategy at this time.

Committee members asked technical follow‑ups during the question period. The committee asked whether a pool thermal blanket had been analyzed; the students replied they had not modeled a blanket but acknowledged from other local work that a cover can be a low‑cost, high‑impact measure. A board member suggested a blanket could be "the lowest cost thing" to investigate. The committee asked whether heat pumped from a cooled community center could be routed to the pool; the students modeled that option early but changed their recommendation because a year‑round positive heat demand would risk degrading ground‑source performance over time.

The students also explained why they did not present a single payback or net‑present‑value number: their faculty advisor asked the team to remove detailed payback estimates because the result is highly sensitive to small changes in interest rates, discount rates, net‑metering assumptions and other site‑specific variables. The students noted Wisconsin net‑metering and federal tax incentives (the Inflation Reduction Act tax credits were cited as available at present) could materially affect the financial case but said a detailed financial model would require more precise site and contract data.

Committee direction and next steps: the committee asked staff to explore a few near‑term, low‑cost follow ups (including looking into a pool thermal cover and whether an energy audit/engineering site assessment could be undertaken) and discussed whether more detailed design work could be integrated into future class projects or a professional engineering assessment. The students left a written report and presentation with the committee for follow up.

Why this matters: the community center and pool together represent a substantial share of Monona’s municipal building energy footprint, so deep retrofits or electrification at these sites could materially move municipal emissions toward the city’s 2040 net‑zero objective if paired with feasible financing and a city‑level implementation plan.