Tag Archives: cost


Earthbag Construction – Earthbag construction uses bags (often polypropylene bags) filled with local soils as building material for walls, floors and roofs. The bags are stacked like blocks and can be curved or angled to create domes or vaulted structures. Earthbag building is very inexpensive as the primary material is just local soils which are free. It is also very sustainable as it uses natural materials and the structures have excellent thermal mass qualities for temperature regulation without mechanical heating or cooling. Earthbag buildings stay cool in summer and warm in winter.

Cordwood Construction – Cordwood masonry uses stacks of firewood logs laid transverse and interlocked to create walls. The gaps are then filled with a lime-based mortar. The technique has been used for centuries and results in very strong, fire resistant and air tight walls. Wood is a very renewable resource and the structures excel at passive environmental controls. Houses can be built very inexpensively using mostly local wood cut from the property or obtained very cheaply.

Coppicing – This traditional woodlot management technique involves cutting back broad-leaved tree species like willow or poplar to a low stump. New multiple shoots will regrow from the stool providing a renewable source of timber. Coppiced wood can be used for roundwood construction, fencing, roofing materials and more. By coppicing woodlots near housing developments an endless supply of cheap, locally sourced building materials can be generated with very little ongoing management costs.

Rammed Earth – Rammed earth construction involves dampening soil and compacting it into forms to create load-bearing walls. The soil may contain stabilizers like lime, cement or fly ash. When done properly rammed earth walls are extremely strong, require no wood, are amazingly durable and regulate temperature well. The structural material is just the soil on site so costs can be very low. Rammed earth homes stay very comfortable without using fossil fuels for heating and cooling.

Cob Construction – Cob is an earthen building material made from subsoil, sand, clay, straw and water mixed into a mud mixture and hand-formed into walls. It has been used for centuries worldwide to create very sturdy homes. Cob structures regulate humidity and temperature passively through the thermal mass. Using locally sourced materials like the on-site soils and straw, very inexpensive cob homes can be built by owner-builders.

Structurally Insulated Panels (SIPs) – SIPs are factory-produced wall, roof and floor panels that consist of an insulating foam core sandwiched between two structural facings like oriented strand board. SIPs go together like interlocking building blocks for extremely high-quality, airtight structures that are far simpler to assemble than conventional stick-built methods. They reduce construction waste and allow much faster building at lower costs than traditional building. SIPs excel at energy efficiency, moisture control and comfort without mechanical systems.

Hempcrete – Hempcrete is a building material made from the internal woody hurd of the hemp plant mixed with a lime-based binder. It sets into a hard material that can be used like concrete to construct monolithic, super-insulated and breathable walls. Hemp is a very fast-growing and renewable crop that needs no chemicals and sequesters carbon from the atmosphere at high volumes. Using hemp and lime from local sources allows the construction of very inexpensive, highly insulating homes that are also fire resistant, pest resistant, moisture regulating and thermal mass structures.

Shipping Container Homes – Surplus shipping containers are increasingly being used as attractive, durable and affordable housing units. With steel frames, weatherproof exteriors and customizable interiors, well-designed container homes can be very inexpensive to construct through repurposing unused containers. Located and arranged properly on a site, container homes can be energy efficient and easily assembled modular structures. Adding small built-on components allows plumbing, electrical and living amenities with minimal additional materials.

Straw Bale Construction – Like cob, straw bale construction uses straw (either in bales or loose) as an insulator within walls constructed using a stabilizing matrix like earth plasters or lime-based stucco. The natural fibers regulate moisture and insulation ratings can surpass many synthetic materials. Using straw and earth facilitates the creation of deep-insulated, breathable structures at very low cost if utilizing bales from on-site agricultural wastes or inexpensive locally sourced bales. Advanced straw bale techniques like Nebraska construction create highly durable load-bearing walls.

The utilization of materials-efficient, passive design principles and available local resources allows the development of homes that are extremely affordable to both construct and maintain. Focusing on natural, renewable and recycled materials that require little processing keeps costs minimized. Locating housing appropriately, combining uses like housing with agriculture and using land sustainably maximizes affordability and liveability long term in an environmentally sensitive manner. With education and incentive, many of these techniques could be applied at scale to address global shortages of adequate living spaces.


The first step is to conduct an energy audit of the building to identify potential energy efficiency upgrades that could be implemented. A professional energy auditor will inspect the building to evaluate areas where energy is being wasted through inefficiencies. They will examine the building envelope (walls, windows, roof), lighting systems, HVAC equipment, appliances/plug loads, and industrial processes (if applicable).

The energy auditor will document the existing equipment, materials, and operations and note where upgrades could result in energy and cost savings. Common areas of focus include improving insulation, upgrading to higher efficiency heating and cooling systems, installing programmable thermostats, switching to LED lighting, improving building automation controls, installing variable speed drives on motors, and upgrading refrigeration equipment. The energy audit report will present recommended energy conservation measures (ECMs) that are technically feasible for the building.

Once potential ECMs have been identified, the next step is to research the costs and potential savings associated with each measure. Obtain quotes from contractors to understand capital costs for purchasing and installing new equipment. Be sure to account for soft costs like design fees, permitting, and commissioning. The energy auditor or contractors should provide estimated annual energy savings in units (kWh, therm, etc.) for each ECM based on building usage patterns and efficiency improvements.

To calculate potential cost savings, the annual energy cost savings must be determined for each ECM. Take the estimated annual energy savings and multiply by the current energy rates paid for that utility. Be sure to use the most recent 12 months of energy bills to establish an accurate baseline for current consumption and costs. Sometimes an ECM may reduce demand charges as well, so accounting for any demand-based cost reductions is important.

Calculate simple paybacks by dividing the installed project cost for each ECM by its annual energy cost savings. Compare simple paybacks to average equipment/material life spans to evaluate if savings will cover costs over the effective life of the improvements. ECMs with paybacks less than 5-7 years are generally good candidates for implementing from a financial perspective.

In addition to paybacks, the expected useful life and expected maintenance costs of new and replaced equipment should be considered. Switching to longer-lasting, more durable products may lower life-cycle costs even if initial paybacks are longer. Potential incentives or tax credits for improving efficiency must also be accounted for as these can significantly reduce upfront project costs and improve overall economics.

To evaluate the total potential benefits, the annual energy cost savings from implementing all recommended ECMs should be summed. This will provide the estimated total amount that could be saved each year by making all of the upgrades. Calculate cumulative savings over time by multiplying annual savings by the analysis period, usually 10-20 years based on average equipment/component lives. Also consider non-energy benefits like improved comfort, air quality, operational savings from optimized controls, reduced maintenance needs, or increased property value.

Performing a detailed energy audit and thorough economic analysis of potential cost savings from efficiency upgrades provides building owners the information needed to prioritize projects, optimize investment decisions, and accurately forecast returns on investment from implementing energy conservation measures. With the growing incentives and shortening paybacks available, comprehensive energy efficiency projects can deliver significant cost reductions while also reducing environmental impact.

Carefully researching and quantifying potential energy and cost savings is key to properly evaluating a building’s efficiency improvement opportunities. A full energy audit followed by thorough analysis of costs, savings, incentives, and financial metrics like payback and return on investment allows owners to make well-informed decisions about optimizing their building’s performance through strategic energy efficiency upgrades. With accurate savings estimates, projects can deliver verified financial and operational benefits year after year.


Offshore wind farms have higher upfront capital costs for development and construction compared to many other renewable technologies due to the associated marine infrastructure requirements such as specialist installation vessels, foundations, underwater cables, and high voltage transmission connections to shore. The specialized heavy-duty turbines also have higher price tags than solar panels or simpler onshore wind turbines. Offshore locations allow the use of larger and more efficient wind turbines that can fully take advantage of the stronger and more consistent winds available out at sea.

A recent report from the International Renewable Energy Agency estimated the levelized cost of energy from offshore wind farms constructed in 2020 to range between $53-84 per MWh compared to just $32-42 per MWh for onshore wind, $36-46 per MWh for solar photovoltaic, $15-30 per MWh for hydropower, and $12-15 per MWh for geothermal energy. The costs of offshore wind have been steadily declining as the technology scales up and larger more efficient turbines are deployed in deeper waters further from shore where wind resources are better. Some recent auctions and power purchase agreements have come in well below $50 per MWh even for projects to be installed in the early 2020s.

As the technology matures and supply chains develop the costs are expected to continue falling significantly. Blooomberg New Energy Finance predicts that by 2030 the costs of electricity from offshore wind could drop below $40 per MWh on average globally and potentially below $30 per MWh in the most competitive markets like parts of Northern Europe and Asia. This would make offshore wind cost competitive even without subsidies in many locations compared to new gas-fired generation. Offshore wind is also projected to decline faster in price than any other major renewable energy source over the next decade according to most analysts.

In addition to lower operating costs over time, offshore wind farms have a major advantage over many other renewables in their more consistent year-round generation profiles with output peaking during winter months when electricity demand is highest. Output is also more predictable than solar due to capacity factors averaging over 40-50% compared to just 15-25% for photovoltaics. The steady offshore winds mean generation matches energy demand profiles better than intermittent solar or seasonal hydropower resources without costly grid-scale battery storage.

Reliable round-the-clock energy from offshore wind coupled with growing abilities to forecast weather patterns days in advance allows power grid operators to effectively integrate significantly larger shares of this clean generation into electricity systems than highly variable solar and maintain higher standards of grid stability and reliability. Offshore sites have fewer space constraints than land-based projects and can potentially be located near heavily populated coastal load centers in markets like Europe and East Asia to minimize transmission expenses.

Offshore wind projects require an extensive multi-year development and construction process unlike the quicker installation timelines for solar farms. This means higher upfront financing costs and risks that get priced into the initial levelized costs per kilowatt-hour calculations compared to less capital-intensive onshore renewables with simpler development procedures. Challenging offshore conditions and geotechnical uncertainties also introduce construction difficulties and greater risks of delays and cost overruns versus land-based facilities. Accessing deepwater locations further from shore for the best wind resources also increases complexities and costs.

Overall while upfront investment costs are higher, offshore wind power is projected to become significantly more cost competitive by the end of this decade as technology improves, supply chains scale, and multi-gigawatt projects are deployed. Key advantages in capacity factors, grid integration, and location attributes position it favorably versus alternatives like utility-scale solar photovoltaic and seasonal hydropower resources especially in coastal markets with strong energy demand like in Europe and parts of East Asia. With power purchase costs likely falling below $50 per MWh at many auctioned projects by 2025, offshore wind will establish itself as one of the lowest-cost renewable energy sources for leveraging oceans to help transition electricity grids to carbon-free systems in the decades ahead.


The cost of renewable energy technologies has decreased significantly in recent years and is becoming increasingly competitive with conventional fossil fuel sources in many applications and markets. There are still some aspects where fossil fuels have a cost advantage today or in the near future depending on location and use. A detailed comparison is complex as costs can vary widely depending on specific project details, regional factors and assumptions about technology advancement.

Renewable energy costs have declined dramatically due to technological improvements, manufacturing scale-ups, and research/development investments over the past decade or more. For example, the cost of utility-scale solar photovoltaic (PV) modules alone has decreased over 80% since 2008. This massive cost reduction has been driven by market expansion as well as innovations that improved conversion efficiencies, manufacturing processes, and supply chain efficiencies. As a result, the total costs of renewable electricity for many applications are becoming competitive with new natural gas generation and new onshore wind energy is already comparable or lower than new coal or gas plants in many locations.

Despite the renewable cost declines, their costs are still higher than more mature fossil fuel technologies in some applications. Existing coal and natural gas plants have already been built and depreciated a large portion of their upfront capital costs, so their operating costs are often lower than building new renewable capacity in those markets. The fuel costs associated with fossil generation are significant long-term operating expenses and can fluctuate based on commodity prices. In contrast, renewable energy generates electricity at near-zero marginal fuel costs once facilities are constructed since they use fuels like sunlight and wind that are free. So over the lifetime of projects, renewable energy may achieve lower long-run total costs even if upfront capital costs are higher.

When integrating energy storage like lithium-ion batteries, renewable energy total costs are still typically higher than natural gas ‘peaker’ plants for applications requiring extremely flexible power sources that can rapidly ramp up and down. Energy storage technology costs are also declining quickly and lithium-ion battery pack prices have declined over 80% in the last decade. With these improving economics and continued scaling of manufacturing and deployment, renewable plus storage solutions are becoming competitive for more applications each year. Total lifetime costs including battery replacement over the system lifetime will require careful analysis versus alternatives.

In addition to direct energy costs, the external costs of pollution, greenhouse gas emissions, and long-term environmental damages should be considered in a full cost comparison but are difficult to monetize and are not always included in standard electricity market pricing today. Burning fossil fuels emits air pollutants like particulate matter, nitrogen oxides, and sulfur dioxide that are linked to public health damages from respiratory and cardiovascular illnesses costing hundreds of billions annually according to some studies. Environmental compliance and emission reduction costs for fossil plants may also increase significantly in the future with further regulation. Renewable energy systems produce little to no emissions during operations so have lower long-term external costs that are harder to quantify upfront but are real economic factors over the lifetimes of power projects.

Considering all these factors and taking a long-term, full societal cost perspective, renewable energy is expected to achieve total cost parity with most fossil fuel technologies in a growing number of geographic markets and applications over the next 5-10 years. Most current energy market studies and analysts project that utility-scale solar PV and onshore wind will be cost competitive with new natural gas generation in all or almost all markets under average conditions by the mid-to-late 2020s if not before. Offshore wind and solar thermal (concentrating solar power) are expected to achieve cost parity with natural gas in more limited applications later this decade or beyond, and new advanced nuclear faces significant remaining cost uncertainties. Renewable energy costs are rapidly declining worldwide and will continue to penetrate new markets as they achieve direct economic competitiveness with traditional thermal generation options over the coming years across much of the world.