Fossil-free building heating; What should you consider?
Fossil-free building heating is a current topic on Norwegian construction sites to reduce emissions of greenhouse gases. The ban on using fossil fuel sources boils down to a desire to reduce the greenhouse gases that are used, among other things. for heating and drying. It is not allowed to use mineral oil, so what are the alternatives?
For many years, Energy Rent AS has supplied fossil-free solutions to our customers for heating buildings, and in this article, we will take a closer look at different solutions for fossil-free building sites. The goal is to be able to supply temporary heating that enables completely emission-free building sites.
Fossil-free building heating
When you are going to start with fossil-free building heating there are several things you have to think about. There should be a desire for power requirements, and here Energy Rent can help with the dimensioning. The need for emitted power, kW, and emitted energy, kWh is often a driving factor for choosing a solution. It is therefore important that the desired effect needs emerge early in the process.
Another critical parameter is the available power. How much electricity do we have available, and where is the nearest connection point? It is of little help to run with electric solutions if there is not enough electricity nearby.
Controlling the desired indoor temperature against the DUT (design outdoor temperature) is an important parameter regardless of which way you want to go. DUT says something about what we can expect from the temperature on the coldest days.
Furthermore, it is good to know the time perspective one is talking about. Is there an urgent need that has arisen, or is there a planned need that will last over a firing season? This is information that can be used to determine which solution is chosen.
When one has discovered the power requirement, available power, desired temperature, and DUT, then we are ready to go further.
Best practice when renting fossil-free building heating
If the energy source is to have fossil-free status, it cannot consist of products from oil production. We are then left with electric heating, heat pump, bio-diesel, bio-gas, and wood chips/pellets. Below we discussed the different solutions available.
1. Electric boiler and electric heaters
Electric heaters, or water-based electric boilers, are the simplest and cheapest solutions from a purely technical point of view. Here we get a lot of effect for the price. With a simple user interface, this is a preferred solution in many cases.
An electric heater is very compact, and easy to move and several can be placed outside the building to spread the power connection/need. Typically you get around a 20KW oven with a power outlet of 32A, 400v/3ph/50hz. These are affordable to rent and easy to use.
An electric boiler is compact and can offer great power with a small footprint. It is able to produce traditional 80/60 which is an advantage as the need for an area for heat release is smaller. Q = k * A * LMTD
An electric boiler mainly consists of heating rods and a control panel. The heat production is not dependent on the outside temperature as we are when using e.g. air-to-air and air-to-water heat pumps. This is a significant advantage that must be taken into account in the assessment.
Furthermore, there is no need for defrosting, which again means fewer sources of error and an even temperature. We usually build mobile electric boilers in containers together with expansion, pumps and other necessary accessories. In other words, we supply a complete mobile electric boiler.
We calculate that 1kW of consumption is 1kW of heat output on electric boilers and electric heaters. What can speak against a purely electric solution is the recent high electricity prices and the large power draw.
2. Heat pump
There are many different ways to obtain heat. Basically, we are talking about air-to-air, air-to-water and water-to-water heat pumps. The terms say something about how we absorb and emit heat. E.g. an air-to-water heat pump extracts heat from the air and supplies it to hot water which is then used for consumption.
Air-to-air heat pump
The simplest and most used heat pump is air-to-air. This obtains heat directly from the outside air via an air-cooled condenser and an air-cooled evaporator. Such heat pumps can advantageously be set with the evaporator in return to achieve the highest possible COP.
The advantage of this heat pump is a compact unit with no need for a water connection, no risk of leaks – and associated risk of frost blast, requires little space, and is easy to move. A very good alternative is fossil-free building heating.
The disadvantage is ice formations on the evaporator in winter when the cold gas is exchanged with the outside air and forms ice in layers which reduces performance. The heat pump will then need to defrost for around 10 minutes every hour, where it sends out warm air to melt the ice and cold air into the consumer.
We prefer to use air-to-air heat pumps with electric peak load, or active dampers that send the cold air out to the surroundings. One, therefore, does not want cold air to be sent into the building during the defrosting process.
The heat pump has a decent degree of efficiency, even if it does not reach quite the level of a water-to-water heat pump. This is because when you have the greatest need for heat, it is coldest outside, and the least amount of heat can be obtained from there. Therefore, it will always be an advantage to have a peak load available to ensure the desired effect.
Air-to-air heat pumps require little knowledge to get started, but require experience over time for optimal operation. In return, this requires little space on the site, and is easy to move around as needed.
Air-to-water heat pump
Consequently, an air-to-water heat pump will have an air-cooled condenser and a water-cooled evaporator, where the heat is obtained from the outside air and heats up hot water. To achieve the highest possible COP, the machine can be placed at a return from the building.
The hot water is heated to around 50-55C and then distributed to various sources of consumption. What is a bit special about heat pumps is that the effect is stated nominally, that is to say for a given area. Normally, the effect will be stated in relation to a given standard, e.g. EuroVent.
Then the effect is given by e.g. 30/35C hot water and +7C ambient, i.e. nominal power. It is precisely here that is something of the heat pump’s Achilles heel. They have a low effect per kroner compared to, for example, the electric boiler and bio-burners. In addition, it becomes a victim of cold winter days, which means that when you need the most heat, it is the least available, and the unit must defrost at intervals.
One of the advantages of an air-to-water heat pump is that it can be paired with peak loads as shown in the picture below. This has many advantages, including that we do not have to dimension the heat pump for 100% of the power requirement. At the same time, we have a backup during normal operation, as well as that it balances out the temperature when defrosting the coil. It has a decent degree of efficiency but does not quite reach a water-to-water heat pump.
This type requires a lot of knowledge and experience over time for optimal operation, and can also be demanding for the project in terms of area for placement.
Water-to-water heat pump
This is the most resource-intensive solution, from the project’s point of view, which must either have excess heat, energy wells, or an external source such as seawater. Normally, you want to use energy wells that are suitable for the purpose. The advantage of a water-to-water heat pump is the stable supply of heat.
Here, care must be taken not to place a heat pump that is too large, as this will be a risk factor for e.g. the energy well. Furthermore, there are requirements for the heat transfer fluid to be used. Energy Rent has very good experience with Kilfrost GEO for use in energy wells.
Requires a lot of knowledge and experience over time for optimal operation. Demanding for the project in terms of planning and location.
3. Bio boilers
Bio boilers have some advantages when we start moving up in efficiency. They require little electricity and provide a lot of power per kroner, which again makes them excellent for larger projects and in cases of urgent need. The equipment delivers hot water of up to 90/70 °C, which makes it compatible with most applications. If lower temperatures are desired, we have additional equipment such as mobile shunts and heat exchangers.
We can supply equipment that burns bio-oil, biogas, and pellets/chips, all packaged in complete mobile centrals for easy use. These solutions are preferred by the industry and larger construction sites that want fossil-free building heating.
HVO100 is a type of biodiesel that meets the EN15940 specification.
4. Service and maintenance of fossil-free building heating
Electric boilers, bio-heating systems, and heat pumps all need service. This involves checking fluids, pumps, pipes, valves, and burners to name a few.
We have a wide network in Norway and are available to recommend a good service partner in your area. In the event of planned or unplanned downtime, it can be beneficial to hire a temporary facility. Energy Rent is happy to help you with fossil-free building heating for your project.
When it comes to electric boilers, these are exposed to soiling and corrosion on the heating elements. The heat transfer fluid must be monitored to avoid leaks and power reduction.
On the heat pump, service and F-gas are key elements to ensure stable operation. Bio boilers need regular service and maintenance on burners biodiesel filters etc. It is also necessary to check for leaks both on fuel hoses and water hoses.
5. Transport of fossil-free building heat
Our equipment for fossil-free building heating is ready for quick dispatch at the agreed time. The heat pumps, electric boilers and bio-heating systems are designed for rough conditions on construction sites.
Complete central units in frames and containers make it easy to move around and we have a wide selection of modular equipment for fossil-free building heating ready for rent.
We transport heat pumps, electric boilers, and biological systems all over the Nordics through our shipping partners, and can always deliver very quickly. Our 24-hour emergency telephone is there for you whenever you need it.
6. Lease agreement for fossil-free building heating
When you rent from us, we guarantee the fastest possible delivery and a large selection of available equipment. You can also add power with the modular solutions to take into account increased power demand or seasonal fluctuations.
With a lease agreement, the need for a large investment also disappears and you can focus your resources on operations. The lease is flexible and can be terminated at any time after the binding period has ended. Should the equipment you rent have problems, we are quickly on-site to ensure continued operation, and we can exchange the machine for a new machine from our warehouse in the event of problems with the machine.
7. You have the experts, which got your back
Our team is ready to help you with solutions, installation, and operation, and to assist you during the rental period. Our key personnel has education in refrigeration technology, gas technician II certification, and steam certificates.
Our equipment has remote monitoring to a large extent together with alarms and quick emergency response, if an accident should occur. We can also assist with operations if desired.
Contact us to rent fossil-free building heating, specialized according to your needs.