The use of the Degree Day Method for meter reading and cost allocation of heat in residential buildings. Can heating costs in apartment blocks be allocated fairly? Online meter reading provides users, building owners or commercial building providers with a number of important information that can be used to adjust and control the performance of the heating system.

Let me remind you here that the online Degree Day Method is based on temperature meter readings at intervals of 15-20 minutes at various rooms within the building. This gives us a perfect picture of the thermal conditions in individual apartments, so that we can see how the heating system is regulated, or how the heat in individual apartments is regulated by the local thermostatic valves on radiators.A daily snapshot of the temperature curve in the winter period can be seen in the picture. The image shows a behaviour pattern of most apartment users. The warmest room is the living room. Using local control in other rooms the user maintains their temperatures 1°C lower. However, the apartment is overheated by about 2°C. From the picture we can see that in the building central temperature control is used and that the night heat suppression is set properly, resulting in a drop in temperature by 2°C. Apartment users can control the heat supply in their apartments directly on their radiators. If they really did so, they would save up to 10% on their heating costs.

 The information about the temperature in individual rooms can be used for detection of apartment users who use their apartments in violation of the occupancy permit decision. That means they have their heating off, causing a significant drop in temperature. At such moment, such apartments become “vacuum cleaners” of heat from their neighbours. It shows that poorly heated rooms suck the heat from the neighbours, as walls of the apartment are not perfect thermal insulators. From our experience, such apartments exist in every building. The reason behind it may not only be only intentional, the apartments can simply be vacant. Their owners may have the impression that within the period of vacancy, they can have their heating off, failing to realize that they “rob” their neighbours of their precious heat.

In the next issue, you will learn more on the impacts on neighbours in terms of cost allocation of heat and how the Degree day method deals with it. If a building is equipped with online meter reading of heat, unheated rooms are very easily detected from temperature overviews in individual rooms of the building. In the graph of average room temperatures/day (6.2.2014) we can see temperatures in individual rooms. This allows both apartment owners or house providers (association of housing unit owner committees) to see how the heating in the building  is performed. Based on these data the association of housing unit owner committee can ask the owner of an unheated apartment to adjust the local regulation on his/her radiators, so that the room temperature could reach the standard of 19 to 21°C.

The Degree day method also allows you to save costs. If you use the Degree day method you can create an overview of temperatures in individual apartments or rooms, as can be seen in the picture, and therefore make a quick analysis of temperatures in your building. Such analysis does not require the education of an engineer to understand. From the graph we can deduct that most apartments are overheated. The temperature in most apartments ranges between 21°C and 26°C. In this building, which we took for an example, up to 80% of apartments are overheated. Here I would like to emphasize that such a situation is certainly not an exception. This can be seen frequently. Almost all the buildings we have in our system are heated in this way. Most homeowners can not afford such high temperatures in their living rooms, because the cost of heating would be a burden for their family budget. In our geographical conditions, heat and hot water costs create a major part of total household costs. The decree 194/2007 Coll., which sets heating rules, says that you should have 20°C in your apartment and 24°C in your bathroom. The perception of thermal comfort is certainly a customary affair. However, when considering it pragmatically, reducing the temperature by 1°C can save you about 4-5% of your heating costs.

In most homes the situation is similar to the practical examples shown here, so it is mostly manageable to reduce the temperature by up to 2° C. This gives us the opportunity to save up to 10% on heating costs without any investment, just by changing the consumption pattern. For example, in the building of 100 apartments, the heating costs average around CZK 1.5 mil. / Year. With optimal savings of 10%/year you will save CZK 150,000 per year. That’s roughly the cost of acquiring the online Degree day method of meter reading of heat for a building of such size. The costs are only slightly higher than if the meter reading of heat supply was done using the cost allocators on the radiators (i.e. RTN method). It’s certainly not an insignificant amount, but this system gives us all the necessary and relevant information for a truly effective management of the heating system of the building.

Let us now come back to the graph of temperature distribution in the building. Besides overheated rooms we can also see rooms that are heated insufficiently.  This may be, as I said, due to consumption patterns of apartment users, but it may also be due to the fact that the heating system is incorrectly hydraulically balanced. It may mean that such rooms could not be sufficiently heated at all. The online system will show us whether, for example, some of the branches of the heating system have lower performance than the other branches. The obtained data from the online system make an excellent basis for an expert you may send for balancing your heating system. Based upon the data, they can perform regulatory interventions into the system without making it blindly, based on theoretical calculation or simply on the basis that someone complains about being cold.

Czech company SOFTLINK, Ltd. has made development of its own radio communication technology since 1993. In the past 5 years, we have focused on the development of radio modules for remote meter reading of water meters, gas meters as well as electricity and heat metres. SOFTLINK develops software applications that provide users with automated processing and evaluation of data that are read on-line from various energy and water meters. Softlink technology is implemented by customers such as the condominiums, housing associations, administration buildings of the central or local government, managers of shopping centres and logistics parks. All our systems being developed are based upon online communication in real-time.

Author: Ing. Jaromír Charvát