A sustainable (a.k.a. eco-friendly) building material is one that minimizes its impact on the environment – whether in its production, use, or disposal – and that can be readily recycled. Building with sustainable materials reduces the amount of carbon involved in the growth, production, and/or manufacturing of the material, thus diminishing the size of the carbon footprint associated with that material. Here we discuss some candidates among the current generation of eco-friendly building materials. Continue reading
What is the Kitchen Triangle?
Working in a kitchen requires you to complete a variety of tasks in order to prepare a meal, the most evident and usual of which are cleaning, food preparation, and cooking. The concept behind the kitchen work triangle is to clearly set out unique locations for each of these fundamental tasks, as well as to create an optimum work area to minimize the distance and effort required to work efficiently in the kitchen. Continue reading
What Are Photovoltaic Windows?
Solar windows, also called photovoltaic or solar glass windows, function as windows while also generating electricity from the sun. Solar windows’ potential impact on world energy generation is enormous. They could be utilized in myriad applications, from greenhouse glazing, to replacing conventional windows in homes, to cladding entire skyscrapers. Solar windows are among the latest developments in building-integrated photovoltaics (BIPV) in which, rather than being applied over it, the photovoltaic element is incorporated into the building’s skin itself. In this article we’ll review what solar windows are, how they work, their advantages over conventional photovoltaics, and future prospects for this rapidly emerging technology. Continue reading
The Importance of Master Planning Your Home
Many people start tackling projects on their wish list without thinking much about the future, resulting in homes that don’t meet their family’s needs, lack any cohesive look, and cost more over the long term. As the old saying goes, if you fail to plan, you are planning to fail. A better approach is creating a long-term plan, or master plan as it is called in the construction industry, that encompasses work you are doing now but also looks ahead to your future needs and wishes. Here are some common considerations to help you start your master planning process. Continue reading
Home Additions: Building Out vs. Building Up
Choosing to remodel your home is a significant undertaking, one that comes with many considerations. This is especially true if you are looking to expand the size of your living space. The first thing you need to decide is if you are planning on “building out” by increasing the footprint of your ground floor, or “building up” by adding a second story. Of course, the right answer depends on your needs and preferences, plus physical and budgetary constraints. In this article we will focus on the pros and cons of building outward vs. building upward. Continue reading
2023 California Energy Code Update for Single Family Buildings
The 2022 Title 24 Building Energy Efficiency Standards (Energy Code or Title 24) updates the currently-enforced 2019 Energy Code. The 2022 Energy Code will be effective as of January 1, 2023. Any projects that apply for a permit on or after this date will be subject to the 2022 Energy Code. This article highlights the key changes to the California Energy Code that will apply to single-family buildings. Continue reading
Transparent Aluminum: A Cutting Edge Material
One of the more recent technologies to emerge in the ever-changing world of advanced building materials is transparent aluminum. It has long been the ambition of architects and engineers to find a material that combines the strength and hardness of metal with the crystal-clear purity of glass. Such a “clear metal” could be used, for example, to construct towering glass-walled skyscrapers whose outer skins are structurally self-supporting, with an absolute minimum of secondary supporting members. Transparent aluminum is a cutting edge-material already being used in specialty architectural applications including blast-resistant and infrared-optical windows.
What is Transparent Aluminum?
Known commercially as ALON, transparent aluminum is made of aluminum oxynitride, a combination of aluminum, oxygen and nitrogen. Before it can end up as a hard transparent armor plate, it begins as a powder. This powder is then molded, subjected to high heat and baked, just as any other ceramic is baked. Once baked, the powder liquefies and then quickly cools into a solid, which leaves the molecules loosely arranged as if still in liquid form. The resulting rigid crystalline structure of the molecules provides a level of strength and scratch resistance that’s comparable to rugged sapphire. Additional polishing strengthens the aluminum alloy and also makes it extremely clear.
Transparent aluminum is a transparent polycrystalline ceramic with a cubic spinel crystal structure. ALON is produced by combining aluminum, oxygen, and nitrogen. Its chemical formula is Al2O27N5.
• Hardest polycrystalline transparent ceramic commercially available.
• 80% transparent in the near-ultraviolet, visible and infrared regions.
• Best material available material in terms of optical quality.
• It is three times harder than steel and four times as hard as conventional silica glass of the same thickness.
• Corrosion and oxidation resistant.
• High flexural strength.
• Good compressive strength.
ALON production begins by introducing a mixture having aluminum oxide and carbon into a chamber, agitating the mixture within the chamber, and heating the mixture to make aluminum oxynitride. The next step involves pressurizing the aluminum oxynitride powder to 15,000 pounds per inch in rubber molds submerged in hydraulic fluid. The obtained material, which is molded and opaque, is heated to 2000-deg C and kept at this temperature for two days. Once cooled, ALON emerges transparent and is then ground and polished for extra clarity and strength.
Applications of Transparent Aluminum
Although the material has exceptional mechanical and optical properties, at present it is prohibitively expensive to produce. For this reason its current application in construction is relatively limited, constrained to specialty applications including bullet-proof glass, blast-resistant windows, and infrared-optical windows.
It is thought that as the material becomes more mainstream, production costs will become less prohibitive. In turn this could lead to its application in more commonplace uses. Specifically, due to its exceptional strength and impact-resistance characteristics, in the near term it’s well positioned to emerge as a superior alternative to conventional safety glass (i.e. tempered or laminated glass) in building applications. In the longer term, it could be a material poised to allow towering buildings whose skins are made of only transparent metal.
For Further Reading:
• Science Daily has published an article, “Transparent Aluminum Is New State Of Matter”, found at: https://www.sciencedaily.com/releases/2009/07/090727130814.htm
• An article, “What is Transparent Aluminum?” can be found at TheConstructor.org. The link is: https://theconstructor.org/building/building-material/transparent-aluminium/561733/
• Surmet, a producer of transparent aluminum, has published several articles about ALON at: http://www.surmet.com/technology/alon-optical-ceramics/
Comprehensive Guide to Solar Panel Types
The push for renewable energy sources has led to a surge in solar energy use. In the past decade alone, the solar industry grew by almost 50%, buoyed by federal support such as the Solar Investment Tax Credit and strong commercial and industrial demand for clean energy. As the solar sector continues to rise, it’s worth studying the backbone of the solar industry: solar panels. This guide will illustrate the different types of solar panels available on the market today, their strengths and weaknesses, and which is best suited for specific use cases.
What is a Solar Panel?
Solar panels are used to collect solar energy from the sun and convert it into electricity. The typical solar panel is composed of individual solar cells, each of which is made from layers of silicon, boron and phosphorus. The boron layer provides the positive charge, the phosphorus layer provides the negative charge, and the silicon wafer acts as the semiconductor.
When the sun’s photons strike the surface of the panel, it knocks out electrons from the silicon “sandwich” and into the electric field generated by the solar cells. This results in a directional current, which is then harnessed into usable power. The entire process is called the photovoltaic effect, which is why solar panels are also known as photovoltaic panels or PV panels. A typical solar panel contains 60, 72 or 90 individual solar cells.
The 4 Main Types of Solar Panels
There are 4 major types of solar panels available on the market today: monocrystalline, polycrystalline, PERC, and thin-film panels.
Monocrystalline Solar Panels
Also known as single-crystal panels, these are made from a single pure silicon crystal that is cut into several wafers. Since they are made from pure silicon, they can be readily identified by their dark black color. The use of pure silicon also makes monocrystalline panels the most space-efficient and longest-lasting among all three solar panel types. However, this comes at a cost — a lot of silicon is wasted to produce one monocrystalline cell, sometimes reaching over 50%. This results in a hefty price tag.
Polycrystalline Solar Panels
As the name implies, these come from different silicon crystals instead of one. The silicon fragments are melted and poured into a square mold. This makes polycrystalline cells much more affordable since there is hardly any wastage, and gives them that characteristic square shape. However, this also makes them less efficient in terms of energy conversion and space, since their silicon purity and construction are lower than monocrystalline panels. They also have lower heat tolerance, which means they are less efficient in high-temperature environments.
Passivated Emitter and Rear Cell (PERC) panels
PERC solar panels are an improvement of the traditional monocrystalline cell. This relatively new technology adds a passivation layer in the rear surface of the cell that enhances efficiency in several ways:
• It reflects light back into the cell, increasing the amount of solar radiation that gets absorbed.
• It reduces the natural tendency of electrons to recombine and inhibit the flow of electrons in the system.
• It allows greater wavelengths of light to be reflected. Light waves over 1,180nm can’t be absorbed by silicon wafers and simply pass through, so they end up heating the cell’s metal back sheet and reduce its efficiency. The passivation layer reflects these higher wavelengths and stops them from heating up the back sheet.
Perc Solar Panels
PERC panels allow greater solar energy collection in a smaller physical footprint, which makes them ideal for limited spaces. They are only slightly more expensive to produce than traditional panels, due to the added materials needed, but they can be manufactured on the same equipment, and can end up having a lower average cost per watt due to their efficiency.
Thin-film Solar Panels
Thin-film panels are characterized by very fine layers that are thin enough to be flexible. Each panel does not require a frame backing, making them lighter and easier to install. Unlike crystalline silicon panels that come in standardized sizes of 60, 72, and 96-cell counts, thin-film panels can come in different sizes to suit specific needs. However, they are less efficient than typical silicon solar panels.
Thin-Film Solar Panel Variations
Unlike crystalline panels that use silicon, thin-film solar panels are made from different materials. These are:
• Cadmium telluride (CdTe)
• Amorphous silicon (a-Si)
• Copper indium gallium selenide (CIGS)
Cadmium Telluride (CdTe)
CdTe has the same low-cost advantage as polycrystalline cells while possessing the lowest carbon footprint, water requirement, and energy payback time of all solar panels types. However, the toxic nature of cadmium makes recycling more expensive than other materials.
Amorphous Silicon (A-Si)
Amorphous silicon panels (A-Si) derive their name from their shapeless nature. Unlike mono-and polycrystalline solar cells, the silicon is not structured on the molecular level. On average, an A-Si cell requires only a fraction of the silicon needed to produce typical silicon cells. This allows them to have the lowest production cost, at the expense of efficiency. This is why A-Si panels are suited for applications that require very little power, such as pocket calculators.
Copper Indium Gallium Selenide (CIGS)
CIGS panels use a thin layer of copper, indium, gallium, and selenium deposited on a glass or plastic backing. The combination of these elements results in the highest efficiency among thin-panel types, though still not as efficient as crystalline silicon panels.
Solar Panel Types by Efficiency
Among all panel types, crystalline solar panels have the highest efficiency. Monocrystalline panels have an efficiency rating over 20%. PERC panels add an extra 5% efficiency thanks to their passivation layer. Polycrystalline panels hover somewhere between 15-17%.
By contrast, thin-film panels are usually 2-3% less efficient than crystalline silicon. On average:
• CIGS panels have an efficiency range of 13-15%.
• CdTe ranges between 9-11%.
• A-Si have the lowest efficiency at 6-8%.
Panel Type Efficiency Summary:
• PERC: Highest (5% more than monocrystalline)
• Monocrystalline: 20% and up
• Polycrystalline: 15-17%
• Copper indium gallium selenide (CIGS): 13-15%
• Cadmium telluride (CdTe): 9-11%
• Amorphous silicon (A-Si): 6-8%
Solar Panel Types by Power Capacity
Monocrystalline cells have the highest power capacity, thanks to their single-crystal construction that allows a higher output rating in a smaller package. Most monocrystalline panels can generate up to 300w of power capacity.
Recent advances in solar technology have allowed polycrystalline panels to bridge the gap. A standard 60-cell polycrystalline panel is now capable of producing between 240-300w. However, monocrystalline panels still beat polycrystalline in terms of power capacity per cell.
Because thin-film panels don’t come in uniform sizes, there is no standard measure of power capacity, and the capacity of one thin-film panel will differ from another based on its physical size. In general, given the same physical footprint, conventional crystalline panels output more power than a thin-film panel of the same size.
Solar Panel Types by Cost
Monocrystalline panels (or modules as they are technically known) carry a hefty price tag, due to its energy-intensive and inefficient manufacturing process with only a 50% yield for every silicon crystal.
Polycrystalline modules are cheaper because they make use of the crystal fragments leftover from monocrystalline production, which results in a simpler manufacturing process and lower production costs.
Among thin-film solar panels, CIGS is the most expensive, followed by CdTe and amorphous silicon. Apart from the lower acquisition cost, thin-film modules can be easier to install thanks to their lighter weight and flexibility, which lowers the cost of labor.
Other Factors to Consider
Temperature performance, fire rating, hail rating, and light-induced degradation (LID) are all factors of relevance when selecting the appropriate type of solar panel.
The temperature of a solar panel can affect its ability to generate energy. This loss of output is reflected through the temperature coefficient, which is a measure of the panel’s decrease in power output for every 1°C rise over 25°C (77°F). Monocrystalline and polycrystalline panels have a temperature coefficient between -0.3% / °C to -0.5% / °C, while thin-film panels are closer to -0.2% / °C. This means that thin-film panels can be a good option for hotter environments or places that experience more sunlight throughout the year.
The International Building Code requires solar panels to match the fire rating of the roof where they are installed. This is to ensure that the modules do not accelerate the spread of flames in the event of a fire. California Building Code (CBC) goes one step further by requiring the whole PV system, which includes the racking system, to have the same fire rating. As such, solar panels now carry the same classification rating as roofs:
• effective against severe fire test exposure.
• flame spread should not exceed 6 feet.
• required for wildland-urban interface areas, or areas with high fire severity and wildfire risk.
• effective against moderate fire test exposure.
• flame spread should not exceed 8 feet.
• effective against light fire test exposure.
• flame spread should not go beyond 13 feet.
Solar panels are also tested for hail impacts. UL 1703 and UL 61703 standards address hail storms, by dropping 2-inch solid steel spheres on solar panels from a height of 51 inches, and by firing 1-inch ice balls on PV panels with a pneumatic cannon to simulate hail impacts. Because of their thicker construction, crystalline panels can withstand hail hitting at speeds of up to 50mph, while thin-film solar panels carry a lower rating due to their thin and flexible nature.
Light-Induced Degradation (LID)
LID is a performance loss commonly seen in crystalline panels during the first few hours of sun exposure. This happens when sunlight reacts with oxygen traces left over from the manufacturing process, which affects the silicon lattice structure. The LID loss is directly tied to the manufacturing quality and can range from 1-3%.
Summary: Solar Panel Types Compared
So, which solar panel type should you use? As crystalline and thin-film panels have their own pros and cons, the choice of solar panel ultimately comes down to your specific property and condition settings.
Those living in a dense area with limited space should opt for highly efficient monocrystalline modules to make the most of the physical space and maximize utility savings. If budget permits, going for PERC panels can lower energy generation costs even more in the long run.
Those with a sufficiently larger property can save on upfront costs by using polycrystalline solar panels, where a bigger panel footprint can offset the lower panel efficiency. However, a larger footprint could also mean added labor costs, so it’s not necessarily cheaper to get a higher quantity of less expensive panels. While the initial cost may be low, it may eventually be offset by reduced efficiency and higher operating expenses in the long term.
As for thin-film solar panels, these are best suited for locations where the heavy and labor-intensive installation of crystalline silicon is not feasible. Such locations can include commercial buildings with tight spaces or thin roofs; compact spaces such as recreational vehicles and watercraft; and areas that require flexible installation instead of rigid paneling.
Keep in mind that solar panels are designed for long-term installation, which can be as long as 25 years. So whatever type you choose to go with, make sure to do your homework to ensure that it’s the best option for your needs.
For Further Reading:
• This Old House has published a helpful guide to solar panel types, “Types of Solar Panels (2022)”. The link is: https://www.thisoldhouse.com/solar-alternative-energy/reviews/types-of-solar-panels
• “Types of Solar Panels for Homes (2022 Guide)”, an article published by Architectural Digest, can be found at: https://www.architecturaldigest.com/reviews/home-improvement/types-of-solar-panels
• Solar PowerWorld Online.com’s article, “What are the different types of solar modules?” is at: https://www.solarpowerworldonline.com/2015/07/what-are-the-different-types-of-solar-modules/
What is a Junior Accessory Dwelling Unit (JADU)?
A Junior Accessory Dwelling Unit (JADU) is an additional, independent living unit created through the conversion of a portion of a single-family dwelling. The State of California recently adopted legislation (SB 13, AB 68 and AB 881) that defines the standards applicable to Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs). One of the most significant changes is a provision permitting both an ADU and a JADU on the same lot with an existing or proposed single-family dwelling. This means that you can obtain two rental units to your property, an ADU plus a JADU, in addition to the main house.
JADU Rules and the Differences Between ADUs and JADUs
ADUs are larger, in many cases up to 1,200 square feet are allowed. A full kitchen (not a kitchenette) is required, as is a bathroom separate from the main house. Depending on local ordinance, its own separate entry, additional or replacement parking facilitation, and owner-occupancy may be required. For both ADUs and JADUs simple ministerial (building permit) approval processing is all that is required: local jurisdictions cannot impose the time-consuming and laborious additional burden of discretionary (aka development) permit processing.
Conversely, JADU features summarize as follows:
• Size: 500 sq. ft. max.
• Placement: Must be within a planned or existing single-family dwelling or accessory dwelling.
• Extension: May include an expansion of up to 150 sq. ft. beyond the footprint of the existing accessory structure, but this expansion is limited to accommodating ingress and egress.
• Exterior Access: A separate entrance for the JADU from the proposed or existing single-family dwelling is required.
• Bathroom: May have it’s own bathroom or one shared with the single-family dwelling.
• Kitchen: Must meet “Efficiency Kitchen” requirements.
• Parking: No parking required for a JADU.
Can the JADU have Interior Access to the Main Residence?
Yes, the attached unit may have interior access to the main residence or attached structure. In some jurisdictions but not all, the connecting door may need to be a 1-hour rated door pursuant to the fire protections in the Building Code.
What is a “Kitchen” vs. “Efficiency Kitchen” and Which is Required?
ADUs are required to have kitchens. JADUs are required to have efficiency kitchens.
A “kitchen” is any room or portion of a room used or intended or designed to be used for cooking and/or the preparation of food and containing all of the following: a sink having a drain outlet larger than 1.5 inches in diameter, a refrigerator larger than 2.5 cubic feet, a built-in permanent cooking appliance typically including a 2-burner gas or 220-volt electric range/oven with a range/hood ventilation system, plus space for food preparation and storage.
An “efficiency kitchen” is a limited kitchen facility that includes a sink, a refrigerator, small electric kitchen appliances that do not require electrical service greater than 120 volts, an appropriately sized food preparation counter, and storage cabinets. In some jurisdictions, gas or propane cooking appliances are not allowed.
Are JADUs Subject to Connection and Capacity Fees?
No, JADUs shall not be considered a separate or new dwelling unit for the purposes of fees and as a result should not be charged a fee for providing water, sewer or power, including a connection fee. These requirements apply to all providers of water, sewer and power, including non-municipal providers. Local governments may adopt requirements for fees related to parking, other service or connection for water, sewer or power, however, these requirements must be uniform for all single family residences and JADUs are not considered a new or separate unit.
Are Fire Sprinklers Required?
Yes, a local government may adopt requirements related to fire and life safety requirements. However, a JADU shall not be considered a new or separate unit. In other words, if the primary unit is not sprinklered, then the JADU must be treated the same.
JADUs offer attractive construction options that make sense in a number of cases. For example, they may share systems with the original dwelling, leading to simpler renovation plans. In addition, they can contain a very simple kitchen with small appliances and share a bathroom with the original dwelling. All of this means that the development costs for JADUs are far lower. While they can be rented out, they’re just as often designed for cohabitation. So if you’re motivated and searching for ways to maximize rental income, home appreciation, and living space, it might make sense to invest in an ADU as well as a JADU; it is your legal right to have both.
For Further Reading:
• The Department of Housing and Community Development has published a helpful guide to JADUs, “Frequently Asked Questions: Junior Accessory Dwelling Units”. The link is: https://www.hcd.ca.gov/policy-research/docs/faqsadujr.pdf
• The County of Santa Cruz Planning Department’s guide to JADUs as well as ADUs is at: https://www.sccoplanning.com/ADU/FAQ.aspx
• City of Santa Cruz Planning Department’s “Standards for JADUs/Jr. ADUs/Junior Accessory Dwelling Units” is found at: https://www.cityofsantacruz.com/home/showpublisheddocument/79262/637275737166700000
6 Types of Home Additions and How to Choose One
A home addition is an improvement project that adds finished living space to an existing home. Sooner or later, an addition is a universal desire of most homeowners. Even homeowners who claim that their house is big enough may, from time to time, want a bigger kitchen, an extra bedroom, or a larger bathroom. That’s where house additions enter the picture. Continue reading