Part one.
The following entry, is only a general in a broad area. If you are interested in my insights, feel free to contact me. We can do something cool together and take your organization to an even higher level.
WHAT IS IT ALL FOR?
Every organization should improve and work on efficiency. The saying that if you are not moving forward you are moving backward should be the guiding motto of every entrepreneur. At the same time, going forward does not at all mean that you have to increase revenue by 50% every year, hire more employees and buy better cars. Attention to detail always pays off, and money should not be the only criterion for success.
I believe that every cost incurred toward doing something good, even if it turns out not to bring a quantifiable income in currency, will be a step forward and bring us closer to success.
If we have the opportunity to save the environment and improve the comfort of our employees, it is already worth looking into the topic. If, in addition, there is money left in our account, we may feel privileged to shout loudly around that we can do it better than others.
In a 5- or 10-year perspective, rising energy prices or the pressure of the European Union’s green legislation, we will be forced to take action on the issues I raise below. Those who start now will achieve an advantage over those who wait until they are put up against the wall.
INTRODUCTION
Winter energy invoices from construction facilities have always caused me considerable surprise with their size. I knew they were the result of heating costs and wondered if something could be done about the issue. In the winter of 2023/2024, courtesy of a friendly construction company, I was able to take the subject apart and draw a number of conclusions.
It quickly became clear that the seemingly trivial topic of heating social containers with electricity consists of a whole range of issues. Both technical and sociological, as well as those related to work ergonomics.
But let’s start at the beginning. We are starting the contract and organizing the construction facilities. We organize or in 90% of cases rent social and storage containers for employees. A standard social container, has walls about 10cm thick, insulated mostly with mineral wool with varying degrees of “densification” and many thermal bridges resulting from simple steel construction. Comparing the insulation of a social container to 20cm of Styrofoam on a single-family building, which is slowly becoming the standard, you get rooms that are not very easy to heat in winter and heat up beautifully in summer. That doesn’t sound economical or cheap, and it isn’t.
What is the container heated with? The simplest electric heater, usually about 2kW. Increasingly, social containers are being equipped with air conditioners with a heating function, but almost no one is taking advantage of this option. Which is wrong, but about that further on.
METHODOLOGY
What and how did I measure? I had a triple social container at my disposal. Two of the containers are connected by the longer side without walls – forming a construction office and attached to them is a sanitary container equipped with two toilets and a kitchenette. The containers were equipped with two electric heaters of 2kW each, two smaller 500W heaters in the toilets, and several small boilers.
Between each of the receivers and the power outlet I plugged in a smart plug equipped with wifi control and power measurement. In addition, in the office area and one of the toilets (I omitted the other because it was not used) I installed control panels equipped with thermometers, which also act as programmable thermostats.
In addition, I supported myself with outdoor temperature data from weather stations available in the immediate area.
WHAT WAS MY PLAN OF ACTION?
First of all, I wanted to collect data on what the real costs are for heating the social containers in the winter months and what the costs are for heating the domestic water. The next step was to collect data on the temperatures in the containers while they are in use, during days off, what the users’ approach is to control and regulate the temperature in the containers.
The next step was to see what possibilities there were for reducing energy consumption by lowering the temperature at night, during weekends, etc. At first in a very discreet way, continuing to go , until users lost patience and took matters into their own hands….
SPOILERS
Electric boilers and domestic hot water
Small electric boilers with a capacity of 5-10 liters, used to heat water in a single tap work really well. The small energy yielding area of the small tank, combined with good insulation, means that energy losses are minimal. In practice, the amount of energy consumed by such a boiler is 90% due to the hot water consumed. And the monthly energy consumption of such a device is about 20kWh of energy. Disconnecting the power supply to such a boiler at night and on weekends, will save us about 15% of energy, too little to make the investment in controlling such a device economically justified.
Electric radiator thermostats
The thermostat of a cheap radiator is worth nothing. Trying to regulate the room temperature with a radiator thermostat mounted on a poorly insulated wall is pointless. As long as we are dealing with a friendly aura (read >10stC outside), such a thermostat still manages. It gets interesting when the temperature drops below zero, for example, and the cold penetrating the wall cools the thermostat’s measuring element so effectively that even a low temperature setting does not stop the heater from running at full speed. The effect is that our radiator is “constantly cold” and the temperature in the center of the room easily exceeds, for example, 26stC.
The case is similar for employees using container-based offices in the winter. Against the wall we will most often find our employee and not his desk, it is well known, no one likes to have their screen looked at. Few people also like to sit with their backs to the entrance. Ultimately, we have a man who is sitting, with his back 20cm from a cold wall, saving himself with a heater and feeling the discomfort of insufficient temperature stability in his environment.
Low humidity
In my experience, container offices are quite overheated by default, but other than the temperature, I’ve never considered what the humidity is like in such spaces. It turns out that it can be really dry at times. Standards assume a proper humidity range of 40-60% depending on temperature. Humidity below 40% begins to be unfavorable for us, and I know many people (including myself) who have problems in such conditions, among other things. Dry mucous membranes and a general feeling of discomfort. Below is a monthly chart for daily average humidity at the construction office in January 2024 and a daily chart for one of the driest days, January 9.
An investment in a humidifier, is definitely one of the cheapest we can make in a construction company. Incomparable in any way to the cost of an irreplaceable employee on L4, and inestimable in terms of the well-being of your people.
Shoes and clothes need to be dried
In the context of damp shoes and jackets, no one has qualms. We set the heater to the appropriate power and by the next morning the equipment must be dry. Try to push through limiting the temperature at night, when the manager’s wet shoes are at stake. I did not dare :). On the other hand, there are proven and good solutions that sometimes people don’t know about, and sometimes they simply don’t have time to think about it.
Dedicated boot dryers work great, for a long time I used such equipment to dry motorcycle boots. A blower with warm air in the shoe, dries it super effectively and definitely faster than putting it down on the heater. A really good investment. The aesthetics of such a solution are also not insignificant… The case is similar with clothes. After a quick research, it turned out that there are many clothes drying cabinets available on the market. Manufacturers of such cabinets mainly target the uniformed services, which probably influences their high price. But it is certainly possible to win the favor and respect of employees with such an investment.
Resin must have heat
One of the weekends in December was very warm for the construction office:
Out of curiosity, I asked if something had happened to make the office so warm. It turned out that due to the plan to use resin on the site, the manager decided to put her in the office for the weekend and prepare her for work. An average daily temperature of over 29stC and constant over 4kW of heating power were probably not necessary, but the inability to set the temperature with confidence made it the only solution. Such needs do not occur every day, but they are certainly worth taking into account when planning to optimize construction facilities . When looking for information about clothes drying cabinets, one manufacturer advertised them precisely by being able to use construction chemicals to maintain the right temperature. Apparently, someone already had this need.
Here we will end the part about insights for now. There are many more. Ergonomics of office work in construction conditions, is most often neglected. Rather than planning and introducing a good culture into the organization, we tend to operate on a “somehow it will happen” basis, and then get used to the state we are stuck in. Construction facilities are a very good field for building prestige and organizational culture, which can result in our good image both inside and outside the organization.
WELL, HOW MUCH DOES IT ACTUALLY COST TO HEAT THE CONTAINERS IN WINTER?
Let me limit the methodology of calculations to the presentation of results, so as not to write a scientific paper out of momentum :). Assuming that, the external area of three interconnected social containers is 160m2, and the average maintained daily temperature inside is 22stC (this is what the collected data indicates), the energy demand of such an office is about 0.5Wh/m2K.
Surprisingly, this value coincides well with the Lambda of mineral wool used for container insulation which is about 0.04W/mK. The result of 0.5Wh/m2K does not fully take into account the impact of weather conditions affecting the transfer and reception of thermal energy from the outside like sunshine levels and wind, but it indicates, quite good workmanship of such containers, their tightness, low impact of thermal bridges on the overall result and so on.
For comparison, the current according to the 2021 standard, the permissible external wall transmittance for residential buildings is 0.2W/m2K.
Thus, depending on the average daily temperature difference, the monthly energy demand for one container but occurring in a configuration for 3 connected containers will be:
- For a 10stC difference in temp. – 192kWh
- For a 20stC difference in temp. – 384kWh
- For a 30stC difference in temp. – 576kWh
Suitable for one free-standing container, which will have one more exposed wall:
- For a 10stC difference in temp. – 260kWh
- For a 20stC difference in temp. – 520kWh
- For a 30stC difference in temp. – 780kWh
The conclusions that come to mind are once that social containers should be combined in the largest possible teams – a single container will consume 35% more energy than a container in a team of 3 connected containers. And two, that during the period when we actually have low temperatures, the energy used to heat the containers can equal the cost of renting or leasing them.
Knowing the historical data on average temperatures in previous years, the price of energy we incur on the back office, and the configuration of the back office, we can estimate with a fairly high degree of accuracy the costs we will incur on electricity from period to period.
HOW MUCH ENERGY CAN WE REALISTICALLY SAVE?
Brief and without wrapping. We can easily reduce energy consumption by 20%, with time improving solutions and training employees I would venture that even 30%. Improving temperature control and optimizing the device of container workspaces alone has the potential to achieve 20% savings. Optimization by using reverse cycle air conditioners as a heat source will allow to reach 30%.
Considering the topic in the context of the costs incurred for the use of 3 containers, they may seem insignificant in relation to the implementation of a contract for a dozen or tens of millions of zlotys. But when dealing with facilities that are much larger, the question of cost can be a serious issue.
We must also not forget that under the conditions of the Union in which we operate, every form of energy is directly converted into CO2 emissions and subsequent taxes. When thinking about saving money, we can’t just think about the invoice from the power company. It is also important to remember that building good habits among our employees will pay off in many different fields of operation.
SUMMARY (First).
I will write about technical issues related to equipping construction sites with solutions to help optimize emissions in future posts. I think the playing field is wide for most construction companies. We can jointly implement many initiatives that will bring financial benefits, be suitable for use in the promotion of the organization and, most importantly, improve the comfort of people on site.
Those interested are invited to contact me directly.