Global Warming and Caplow Manzano

How high performance and design for life can help save the planet

by Ted Caplow, PhD

Twenty percent of greenhouse gas emissions in the United States are caused by supplying energy to homes.¹ By the middle of the century, the United States is expected to build up to 100 million new homes,² and many of these will be larger than homes of an earlier generation. In order to combat global warming, comply with international agreements, and reduce emissions substantially over the 21st century, a new approach to home construction will be needed.

For the purposes of this discussion, we will use energy consumption as a reasonable substitute for greenhouse gas emissions, because energy impacts are easier to measure, predict, and compare.

Consider the energy impact of operating an average new Florida home that is the same size as Caplow Manzano’s newly finished CM1 (which is a 2,600 sqft, 3-bedroom residence in the Silver Bluff neighborhood of Miami). An average new home this size is expected to consume approximately 1.5 million kwh of energy over a 55 year lifetime, from construction through demolition.³ ⁴

CM1 is a very efficient house. By encapsulating insulation inside the concrete block walls, incorporating high performance windows and doors that reject solar radiation, and using efficient, ductless room-by-room air conditioning systems, CM1 will consume only 49% as much energy as an average new home of the same size.⁵ Other design choices that contribute to these efficiency gains include insulating above the roof slab and below the floor slab, and reducing thermal bridging areas of the structure that can convey unwanted heat into the home.

But what about the energy needed to build the home in the first place? Based on national averages, the construction of most homes will account for about 15% of their total lifecycle energy impact.⁶ This portion is called “embodied” energy, required to form and assemble the physical materials that compose the home.

With homes like CM1 that are so efficient to operate, the embodied energy represents a larger share of the total impact and becomes an important area for sustainable measures that reduce impact. At Caplow Manzano, we use durability to mitigate impact: our homes are designed to last at least twice as long as an average new home in Florida. Rather than aiming for 50 or 60 years, CM1 is designed to last well over 100 years.

Caplow Manzano designs for longer lifetimes through selecting durable materials (especially concrete and masonry), eliminating weaknesses against water intrusion and decay (following our hypostruction philosophy), and elevating far above today’s streets to prepare for a century of rising seas and associated storm surge levels. From a material standpoint, a house that lasts twice as long replaces two houses that would be built one after another in its place, cutting the embodied energy in half.

If we also account for the fact that CM1 is 20% larger on the inside than a typical home (thanks to removing the hollow space found inside the walls and ceilings), the energy and material impact per unit of occupied space drops to only 40% of an average new home’s impact.

However, Caplow Manzano goes a step further: the large (11.5 kW) solar array on the roof of CM1 is expected to produce as much energy over the course of a year as the house consumes.⁷ This big kick of clean power pushes the home towards “net-zero” energy impact.

Time will tell if the building performs as expected, but modeled results suggest that Caplow Manzano’s CM1 will be 17 times more energy efficient than a normal house,⁸ over the course of its 100+ year lifetime. With the housing sector responsible for a whopping 20% of our total greenhouse gas emissions, creating more buildings like CM1 represents critical progress towards reducing global warming.

¹ https://www.pnas.org/doi/full/10.1073/pnas.1922205117
² ibid
³ Average consumption of a 2000 ft2 home in Florida: 1642 kwh/mo (https://gitnux.org/average-kwh-usage-for-2000-sq-ft-home/); this figure matches internal modeling by Caplow Manzano using Energy Gauge™ software.
⁴ The average lifespan of a home in the U.S. is estimated at 50 - 63 years (https://architecture.mit.edu/news/architectural-longevity-what-determines-buildings-lifespan). Note that the lifespan is different than the average age of current homes, which is closer to 40 years. The growth in single family homes over the last century accounts for this difference between the life expectancy and average age of houses.
⁵ Caplow Manzano uses FL-authorized Energy Gauge™ software to model building performance. The same techniques are used by our third-party energy auditors to certify our LEEDTM performance.
⁶ https://www.frontiersin.org/articles/10.3389/fbuil.2022.975071/full
⁷ Prediction of solar energy production based on array size and orientation by Energy Gauge™ modeling software, confirmed by a third-party solar consultant.
⁸ CM1’s solar array, if maintained in a fully operational condition, is modeled by Energy Gauge™ to offset operational consumption for net zero performance; note that this estimate conservatively assumes no increase in panel efficiency or array size over the home’s lifetime. Per the text above, embodied energy is 40% less than an average new home (in turn estimated as 15% of lifecycle energy consumption). The combined reduction, operational + embodied, is thus 94%, or a factor of 17 times.