Commercial sector - Heat Changers Blog

The biggest problem is not only the high water consumption of hotels, but also the energy used to heat it. By harnessing solar energy, hotels can ensure significant savings, reduce their carbon footprint and offer a greener experience to their guests.

The overlooked energy drain in hotels: hot water.

Hotels consume massive amounts of hot water daily—from guest room showers and jacuzzis to pools, spas, kitchens, and laundry facilities. Heating this water represents a significant share of a hotel’s total energy use, often relying on costly and carbon-intensive fossil fuels. This drives up operational expenses and contributes to climate change.

In terms of temperature, hot water requirements in a hotel vary depending on its specific use:

Between 40 and 60°C are needed to ensure adequate hygiene in bathrooms, showers, jacuzzis and sinks in rooms, as well as for cleaning processes in kitchens and laundry rooms.
To effectively disinfect sheets, towels and textiles in the laundry, the water must reach a minimum of 60°C.
Pools are usually kept between 24 and 30°C, depending on the climate and the desired comfort. In luxury hotels or wellness resorts, jacuzzis and hot tubs require higher temperatures, generally between 35 and 40°C.

In many parts of the world, room heating is powered by hot water. Underfloor heating systems operate at temperatures between 40 and 50°C, traditional radiators may require up to 80-90°C to provide efficient heating in cold climates.

Energy consumption associated with water heating varies by hotel category and location. According to the Hotel Energy Efficiency Guide published by the Mexican Ministry of the Environment:

In 5-star beach resorts, heating water accounts for 26% of total energy consumption.
In 3-star city hotels, this figure can rise to 42%, making it the single largest energy expense.

Traditionally, water heating works based on systems that use LP gas, natural gas or diesel as energy sources, which implies high operating costs, CO₂ emissions and dependence on the volatility of fuel prices.

According to the Spanish Institute for Energy Diversification and Saving (IDAE), a 3-star hotel consumes an average of 41 liters of hot water per person per day. In an establishment with 100 double rooms and full occupancy, this is equivalent to 8,200 liters of hot water per day, which requires approximately 30 m³ (30,000 liters) of natural gas or 23 m³ (11,500 liters) of LP gas per day.

A smart, sustainable alternative: solar water heating systems

Hotels need a reliable, cost-effective way to heat water without increasing their carbon footprint. Solar thermal technology offers the perfect solution. Unlike gas-powered systems, solar water heaters use free, renewable energy from the sun—cutting operational costs and reducing emissions.

How solar water heating works

A solar thermal system is designed to efficiently capture, store, and distribute solar-heated water throughout the hotel. It consists of:

Solar collectors: these absorb sunlight and convert it into heat. Unlike photovoltaic panels, which achieve 20–30% efficiency in electricity generation, solar thermal collectors utilize 70–80% of solar radiation to heat water. Different types include evacuated tubes, flat plate collectors, and polymer absorbers.
Storage tanks: heated water is stored in insulated tanks to ensure supply even when the sun is not shining.
Backup heating system: the existing gas boiler becomes a secondary system, activating only when needed. For even greater efficiency, hotels can replace traditional boilers with heat pumps that work in tandem with solar energy.
Control and monitoring system: remote monitoring allows hotel engineers to track performance, optimize energy use, and detect any issues before they become costly problems.

Why solar water heating is a Game-Changer for hotels

Beyond sustainability, solar thermal systems offer several key advantages:

Lower operating costs and fast ROI

Fuel prices are volatile, but solar energy is free and stable. Depending on the location and the cost of fuel replaced, the return on investment (ROI) of solar heating systems is surprisingly fast. In an ideal scenario: a location with abundant solar resources in a temperate climate and high fuel costs, the ROI can be between 2 and 3 years.

2. Seamless integration and minimal disruptions

Solar heating can be installed in both new and existing hotels without interrupting hot water supply. It works alongside existing infrastructure and can be gradually expanded to meet growing demand.

3. Long-term durability and low maintenance

A properly installed solar thermal system lasts up to 25 years, with maintenance limited to periodic cleaning and inspections.

4. High recycling potential and sustainable supply chain

- More than 95% of system components (stainless steel, copper, and glass) are recyclable.
- Unlike other renewable technologies, solar thermal systems do not require rare or critical materials, making them accessible and locally available in most markets.

5. Financial incentives and green financing options

Hotels can take advantage of:

Tax benefits (deductions, accelerated depreciation, or subsidies).
Flexible financing models, such as leasing or Heat Purchase Agreements (HPA), where the hotel pays only for the energy produced rather than buying the system

Proven success: hotels that have made the switch

Hotel Central Abastos (Guadalajara, México)

In this hotel, 30 flat-plate solar collectors were installed that occupy an area of only 60 m² on the roof. The system generates 5,000 liters of water at 55 °C daily. The high efficiency of solar thermal collectors (70 – 80%) allows the rest of the space to be used for the generation of electricity with photovoltaic panels.

The solar thermal system meets the demand for hot water for the rooms, laundry and public bathrooms located in the same building. Minimal adjustments were made in the machine room and there was no major investment since the hot water storage tanks that already existed were used. LP gas boilers operate as a backup at night, drastically reducing fuel consumption.

Hostería Las Quintas (Morelos, México)

This hotel took solar heating even further:

Installed 62 flat plate solar collectors (124 m²) for guest rooms and services.
Added 35 polypropylene collectors (133 m²) for two swimming pools.
Equipped the system with 15 storage tanks, holding 8,500 liters of hot water.

Solar thermal systems are placed on several rooftops of the hotel. In the months of greatest solar radiation, the boilers operate only 30% of the time, mainly at night.

Thanks to this system, the hotel saves 16,850 liters of LP gas per year, which represents a saving of 156,049.52 Mexican pesos annually. In addition, 27 tons of CO₂ per year are avoided.

The return of investment was three years.

Sustainability as branding strategy

Integrating solar water heating into hotel operations isn’t just about cost savings—it’s about building a future-proof, eco-conscious brand.

Earn green certifications (LEED, EDGE, or national sustainability seals).
Attract eco-conscious travelers who prioritize sustainable accommodations.
Enhance your hotel’s reputation as an industry leader in sustainability.

To sum up: the future of hospitality is solar!

Solar water heating offers an immediate, effective, and proven solution to cut costs, reduce emissions, and improve their sustainability credentials.

Article written by Marisol Oropeza.

Heat: Understanding its Role in the Energy Transition

You may not know it, but solar energy is also heat! This is a call to action for hotels, spas, restaurants, hospitals, educational, leisure and sports facilities! Are you ready to include solar thermal energy in your facilities?

Businesses and organizations in the service sector are quick to source their electricity from renewable sources such as photovoltaics, but they are not so quick when it comes to thermal energy or heat. Today, there are affordable and reliable solutions that accelerate the transition to clean energy across the board in the service industry. Basically, it is about using the same sun to cover their heat demand (hot water) with solar heating technologies. However, this most in-demand use is being overlooked in the energy transition efforts.

Imagine a cake divided into three different sized pieces, and everyone wants the smallest piece and leaves the biggest one aside. The cake represents the final energy use, divided into three: electricity, transport and heat.

Although it is the smallest segment, electricity is the main target, with up to a third of electricity generation being covered by renewable energies. This is followed by energy generation for transportation, which poses other challenges. But thermal energy, which is the largest share – almost half of the cake– is still dependent on fossil fuels, as it has only managed to cover slightly less than 10% with renewables.

Solving this problem is our specialty.

Solar Thermal Energy for All Needs

First, what is solar thermal energy for? To get the same as we get with any fossil fuel: heat. Solar thermal technologies supply energy for different temperature requirements:

Low temperatures: For processes that require no more than 302°F (150°C), such as cooking, cleaning, pasteurizing, sterilizing, drying, steaming, simmering and pickling.

Medium temperatures: Ranges from 302°F to 752°F (150°C to 400°C) and is ideal for distillation, nitrate melting, dyeing and compression processes.

High temperatures: Yes, it can generate the heat needed for material transformation processes or to drive turbines that require more than 752°F (400°C).

Where Can Solar Thermal Be Used in the Service Sector?

The majority of the service sector’s heat demand is in the low temperature range and can be met by long-life, low-maintenance solar thermal systems.

Here are some examples:

Hotels, resorts and spas: for pool heating, water heating, laundry, kitchen and space heating.

Sports and leisure centers: similar to above, for pool heating, hot water for showers and steam baths, laundry service, cleaning and disinfection.

Restaurants and cafeterias: for hot water for sanitization, for brewing and for cleaning and disinfection processes.

Healthcare centers: Hot water for sanitary use, space heating, disinfection, cleaning and sterilization.

Decarbonizing with solar thermal is a goal of Will Giese, Senior Director of Government Affairs at Solaray Corporation, the parent company of SunEarth. We spoke to him in our podcast about the potential applications and scale of solar thermal in the United States. He points out how businesses leaders have started to think hard about where energy in commercial buildings comes from whether its renewable or not, whether its low-carbon or not.

“Solar thermal is kind of the ultimate energy efficiency measure through thermal generation. It makes everything better! If you go and look at solar thermal systems paired with gas backup systems, the greenhouse gas emissions reduction is quite a lot because the solar thermal system is working most of the time and your gas system really works as back up.”

Will Giese

Senior Director of Government Affairs at Solaray Corporation

What Benefits Can Business Expect with Solar Heating?

The most important: a better world. Committing to these changes in the private and public sector means accepting that our contribution will help tackle climate change by moving towards the goals we need in the world. Switching to solar thermal leads to an immediate reduction in greenhouse gas emissions, making our carbon footprint smaller and smaller.

Here are some benefits of switching to solar thermal in the service sector:

Economic: Although some businesses may dread this financial decision, switching to solar thermal immediately reduces the cost of electricity or gas for hot water by up to 70% over a period of up to 25 years. In addition, in many countries there are benefits and subsidies for those who opt for renewable energy. In the USA for example, thanks to the Inflation Reduction Act users can get an additional 10% a tax credit for installing US-made solar heating systems.

Environmental: Yes, we’ve already said that it helps to be part of building a better world, but reducing the company’s carbon footprint goes beyond ending direct consumption, it also extends to shortening supply chains and cleaner air and water.

Social: The benefits extend to the communities and cities we live in, to those working in the solar industry, promoting technology development, boosting a local and decentralized economy, demonstrating an interest in contributing to our society, leading by example and championing change.

Reputation: Heat Changers do not like greenwashing and reputation goes beyond a label saying “eco” or “organic”. Actions that significantly reduce the negative impact of economic activities on the environment not only help to meet global emissions reduction goals, but also demonstrate the commitment of companies to offer a truly sustainable service, which is preferred by more and more customers.

Another example of the benefits of solar thermal that goes beyond the service industry is its use in low-income housing. Will Giese pointed out the importance of using solar thermal in this sector. While this is a challenge because it is difficult to finance, these projects can improve the efficiency of multifamily buildings and reduce costs for people, bringing social, economical and environmental benefits.

If There Are Two Solar Technologies, Do You Have to Choose One?

No. It is all a question of correct energy diagnosis and dimensioning. There are suppliers who install both technologies to make the best use of the space and the solar resource. Another big advantage of solar thermal is its efficiency, i.e. how much heat the collectors can provide with the available solar energy and space.

The efficiency of solar thermal collectors is between 70 and 80 % (i.e. they use almost all of the solar radiation to do their job), whereas the efficiency of photovoltaic modules is 20 % at best. Therefore, solar thermal collectors require much less space to meet the largest demand (the biggest slice of the cake) and thus make room for electricity generation (the smallest slice of the cake).

How Do You Offer a High Quality and Sustainable Service?

Switching to solar energy offers freedom and security, even if some companies are reluctant to take this step. However, if we have convinced you, we recommend to get closer to specialists in this field who are part of our community. It is important that you evaluate the offers of the different providers in your area so that they can make a correct diagnosis of your consumption and processes, resolve your doubts and explain the technology that best suits your needs.

The solar market is as diverse as the needs that companies and people have. Will Giese give us an example: in Hawaii, solar thermal sector is the strongest than any other US state because energy prices are high and dependent on fossil fuels. There is no natural gas in Hawaii, so heating needs must be met with electricity, making the switch to solar thermal a smart decision.

However, the context of the needs can be different, from the commercial activities to the industrial ones. For example, according to Will Geise, companies such as Amazon, Wal-Mart or Target can fully convert their warehouses to solar thermal more quickly. Yet, for industrial companies whose production is highly dependent on energy prices, it can be more difficult to decide on a single energy source, as many other decisions have to be made, such as location, prices or taxes.

So, if you are in the process of switching to solar thermal, there will be always a solution for your business that will be personalized and efficient.

Author: Laura Yaniz Estrada, Communications Consultant.

Category: Commercial sector

Greater sustainability in hotels with solar energy