Ideal sustainable homes and building practices

Note that recommendations favor natural materials (wood superstructure, cellulose insulation and rockwool rigid board); these have proven to be renewable when managed effectively. Even though asphalt shingles contain fossil fuels, they are recyclable at end of life, and compared with other roofing materials, they represent the best combination of environmental and economic benefit. Finishes, equipment, and appliances are recommended to be basic, standard, and simple, not only for less environmental impact, but because they also offer the best financial value and return.

In most areas of the U.S. a single family house with these features can be built for $100 per square foot or less. Using the guideline limit of 2,000-2,500 square feet, maximum cost for new construction should not top $200,000-$250,000, and this can be achieved for much less for smaller houses. Additionally, houses with these features are very likely to appraise at or above constructed cost, in most areas and markets, making it possible even for low asset buyers to secure financing. With solar PV producing all the (net) energy needed to power both household and transportation, this package immediately removes about half of the ecological footprint of the household and its occupants. Further, if finishes and equipment are held to simple baseline standards, this package is the least costly. Even though the solar investment seems large initially, the continuous stream of benefits make the energy system less costly than most utility rates (see Chapter 3).

This big picture building package is so counterintuitive and counter-conventional, that it bears repeating for simplicity, clarity, implications and impacts:

The conventional wisdom has drifted so far from what the data and current possibilities support, that a shift now from common understanding and application to this more sustainable package offers win-win outcomes. What we are terming the SOLO House offers these nine benefits:

People building a new home typically find it very difficult to resist cost creep; adding a bit of space here or an upgraded appliance there. Each individual upgrade or size expansion seems small in the decisive moment, yet the collective impact of several or many of these choices can be enormous. Adding livable space not only increases cost and resource use at construction, but it commits the owner (and society) to maintain and condition the space continuously thereafter. There is another tragedy of this phenomenon from an ecological perspective, and that is the opportunity costs that people do not always consider. Homeowners too often tap out their assets (or budget or financing) with many small upgrades and then find solar PV or transition to EV unaffordable. Priority must favor onsite solar PV!

Passive solar could be pursued, if the orientation is ideal, and if it adds little to no cost, though review Chapter 6 for assessment of trade-offs and complexities. However, from an opportunity cost perspective, as well as for environmental and financial return, passive solar should not be wedged-in if it comes at the sacrifice of active solar and EV transportation. Still, if homeowners desire windows for natural light or ventilation, designing for their placement on the south side will get the most out of these weak links in the thermal envelope. Here is an example of a 3-bedroom, single-story, ranch-style home with most windows on the southern elevation. This mild-passive design can be achieved without adding cost.

This design and orientation also provides an ideal roof space for active solar PV. With the ridge of an A-frame roof running east-west (a low-cost structural design) the south pitch of the roof provides an uninterrupted pitched plane for the solar array; the angle of the roof could be optimized for solar production based on latitude, though roof cost should also be considered. The house plan above could also be considered ideal in meeting other criteria, as it is single story and could be anchored by a concrete slab foundation.

Professional Services

Working with an architect on a residential project is typically optional. Certified engineered plans can be downloaded from the web or purchased wholesale; builders may also provide plans that have been reviewed and permitted in previous work. Since employing an independent architect would add to the overall cost to the project, homeowners should carefully consider the value proposition. Earlier in this chapter we wrote about the potentially large explicit and hidden costs of adding footprint space to a house design. A skilled architect could more than pay for their service fee by designing or redesigning plans to reduce or eliminate wasted space; they are also trained to find efficiencies. Hallways and steps are cost and space wasters, but a good architect might find alternative design to avoid them, or to creatively use space in or around them. If an architect can eliminate 80 square feet from the footprint with more efficient design, they will have saved the homeowner roughly $8,000 in construction cost, and there will be lifetime savings in conditioning and maintenance.

Architects are better known for their value in adding artistic and aesthetic design; that could be a bonus if an architect more than compensates for their professional fee by lowering construction and operating costs. However, since architects have no personal or professional incentive to contain costs on behalf of others, some may prioritize design and aesthetics over budget. Some architects may not be as deeply driven by values around energy, environment, or sustainability. Finding the best match of principles and values will be important for the homeowner; here is a list of criteria we recommend employing to interview and select an architect:

Homeowners who want to be environmentally responsible in the house they build or renovate, will need some expertise on design, materials, energy, equipment, and quality control. We think a homeowner with a little bit of construction experience and savvy could use a resource like this book to provide or organize these decisions, but most will do well to rely on the professional services of an informed architect. An architect can also be an objective accountability source for the builder and can provide oversight, quality control, and inspection. We have noted in several contexts the importance of quality craftsmanship in construction; it is only on that basis that we are confident to recommend code-minimum structural standards. If the homeowner does not have another source for effective quality control, we strongly recommend hiring an architect, who will also provide the services listed above as a bonus.

Selecting a builder is one of the most critical decisions in new home construction, and many homeowners struggle with the process and choice. The most common approach in the U.S. is to invite several competitive bids based on a set of plans, but homeowners may lack necessary expertise or experience to effectively evaluate and compare proposals. The lowest bid may not result in the lowest overall cost, depending on included scope, contingencies, and change order management. There may also be vast differences among contractors in communication skills, adherence to schedule, quality craftsmanship, and professionalism (working relationship). This highlights another benefit of employing architectural services; an architect should serve as an advocate for the homeowner in communication and decision making with the primary builder, and other industry professionals.

An architect could also manage a bid or negotiation process with contractors to help the homeowner select the builder and negotiate the contract. Architects are likely to know the reputation of builders in their region to help guide the best match with a homeowner and their specific interests. If the homeowner connects with a builder that they already know and trust, negotiating a contract can be done with integrity if an objective third party (as in an architect) can validate rates, processes, price and schedule. That would avoid the competitive bid process that incentivizes contractors to pare proposals to be competitive initially, but that later encounter disagreements over scope, potential cost overruns, and possibly personal or professional conflicts.

As with architects, builders do not have the same incentive as homeowners to contain costs; however, a few processes can be employed to keep all stakeholders appraised of changes that have implications for cost or schedule. We have a list similar to architects in interviewing and selecting a builder, and then some recommendations about managing assumptions and communications throughout the project:

The big decisions of overall building size, design, and structure are made before the contract is signed and construction begins. It is the myriad smaller choices that need to made along the way that become challenging for a wide variety of reasons. Windows, doors, paints, appliances, faucets, light fixtures, trim style, cabinets, countertops; this is just a subset of a list that seems endless. These selections, as they are termed, need to made by the homeowners because they reflect personal preferences and cost implications. Builders often handle the delicate issue of selections with allowances. These lump sum amounts per category are helpful initially to estimate their contributions to the overall contract, but it is very difficult to monitor impact of each decision as they are made rapidly throughout the project.

Whether or not the builder employs the allowance mechanism, starting with shared knowledge of the cost and specifications of baseline selections allows homeowners to evaluate potential upgrades on the basis of price premium. If the selections list is then updated as decisions are made, the homeowner can track impact on both category allowances and the overall contract; it would also allow them to consider opportunity cost implications throughout the project. Stated more simply, prices must be attached to every choice beyond the baseline benchmark so that homeowners can make informed decisions knowing the implications. This level of transparency is generally lacking in the building industry.

Since very few (if any) upgrades return operational benefits that would allow the cost premium to break even over its expected life (Chapters 5-7), homeowners can consider upgrade premiums as driven by personal preferences. Each upgrade, and the accumulating costs, can then be assessed against alternative use of limited funds; the opportunity costs. If premium selections are driving the homeowner away from solar PV or EV transition, those choices have enormous implications for the household ecological footprint. Sharing live and updating documents can check homeowners against their budgets and overall goals and objectives.

Renovating Sustainably

The findings of this study lend greater support for renovating older buildings rather than demolishing and starting anew. The prevailing notion that bigger, thicker, and more robust thermal envelope elements provide unquestioned benefits in reduced heat loss and energy bills, immediately places older structures at a perceived disadvantage. However, if the structure of an older building is sound, or it can be bolstered where needed, our conclusions suggest that it is preferable from both a dollar cost and environmental perspective to use what is salvagable instead of unnecessarily adding waste to a landfill and demanding fresh resources.

Due to diminishing returns on the most insulated sections of the thermal envelope, and the fact that building codes in the U.S. already require more insulation than the net marginal benefit (NMB) optimum, rebuilding the thermal envelope beyond what code requires returns negative NMB, both financially and environmentally. Financial returns are negative because significant premium costs are never recovered by relatively small benefits in operational savings. Environmental returns are negative because the additional embodied energy of thermal envelope upgrades, either beyond code compliance, or in full in the case of a rebuild, are not fully offset because operational energy savings are relatively small.

The primary concern in any renovation project, and the first dollars committed, should be to transition the building to a clean(er) and renewable energy source. In the U.S., that most often means installing enough solar PV to displace fossil fuel laden, utility-provided, electricity. Remember that solar PV in most U.S. regions is less expensive over the life of the system than grid-provided energy, and since solar PV is the optimal system for distributed small-scale onsite energy generation, a renovation may provide opportunity to rework or reorient solar capture zones.

Arguments outlined in this book acknowledge weak links in the thermal envelope as features that diminish the relative value of the most insulated elements. Even in new construction, therefore, the best spending on thermal envelope upgrades–if any–should address weak links first. Typical weak link elements, such as windows, have improved significantly and relatively more than stronger elements over the past two decades; therefore, the gap between weakest and strongest elements of the thermal envelope is wider in older buildings. This gives stronger rationale to upgrading the weakest links in renovating older buildings, and weaker rationale to upgrading the strongest elements. The following chart offers a ranked priority list in building renovation; note that these recommendations generally support better financial returns and lower environmental impact.

One of the tragedies of many renovation or rebuilding projects is the loss of heritage; the history, culture, design, and style from the past. While demolition and rebuilding is necessary in cases where the structure is sufficiently compromised, historical and cultural treasures rarely need to be sacrificed in the name of dollar cost or ecological responsibility. Each case is unique, and there may certainly be exceptions; however, our analysis of financial return and ecological impact in the building process will almost always favor renovation over rebuilding, if the structure is salvageable. Adding solar PV can be achieved in discrete ways that retain the historical appearance. Keeping waste materials out of landfills, and reducing extraction and processing of new building materials, extends the utilization of scarce and limited resources. The reoriented thinking and priorities unearthed in this comprehensive view of energy and materials should reorient the calculus on when to demolish and rebuild, and how to prioritize renovations.