Domusplus – experiences in BIM implementation

BIMcert got the opportunity to experience real life implementation of BIM in a small/medium sized construction company DOMUSplus ltd. specialized in developing and construction of prefabricated energy efficient single family homes in Croatia through the interview with company co-owner and director Mr. Hrvoje Kuretić. We are grateful for open answers which show both the obstacles and opportunities for a company developing in very competitive market.

BIMCERT: Your company has grown significantly in last five years?

DOMUSPLUS: We experienced expansion before four or five years. Since 2006, when Domusplus was established, we have continuous growth of 30% annually. It is particularly strong in last two or three years, when our capacity increased from twenty units annually to fifty or sixty. Our production isn’t actually measured in number of units (family homes) anymore, but in total built area. Last year’s output was 7.000 m² of houses. This year, it will be 8.000 m², and next year’s goal is 10.000 m². We also built new production facility, bought new equipment, and actually doubled our capacity compared to few years back. Processes which took two or three days are now completed in literally two to three hours – just sending the file to the factory, having someone to feed the material in the machine which automatically draws, marks, saws… Right now, we employ over 50 people, which is a large number for us.

BIMCERT: This is automated, or semi-automated production then? Have the processes in the company been structured from the beginning, or are you adapting them as you go?

DOMUSPLUS: We’re still setting the up. Two years ago, BIM idea emerged here, and we invested in software purchase – specialized software for production of prefabricated wooden buildings which we do. Primary, this is SEMA software – specialized software for wooden prefabricated houses, which covers development of prefabricated constructions, walls, slabs, roofs, any other elements (SEMA allows bidirectional communications through standardized IFC format). Software is linked to machines in our factory. It has been upgraded through various modules and followed by continuous education in software use. software investment amounts to approximately 100,000 euros and now we are seeing payback on our investment. Two years ago we initiated the project which will incorporate the entire process from the initial idea developed in ArchiCAD through Dlubal software for construction analysis, further connected to production development software. We are using single architectural model for construction and workshop drawings and with two clicks we can produce final plans within half hour. This is still an idea but I hope it’s going to become operational by the beginning of next year.

BIMCERT: So, all the business processes in the company connected through BIM. you already connected the preliminary plan to production, cost estimates, time planning…   

DOMUSPLUS: Yes, one thing follows the other. we couldn’t maintain manual labor an Excel spreadsheets. we had to invest to follow the growth of the company.   

BIMCERT: What remains? I know that you are doing building physics calculation within the national regulation. Are you preparing yourselves for energy simulations – next step – optimization of the building fabric regarding the energy demands? BIMcert project addresses that particular issue in training for increased energy efficiency in entire construction sector production chain. 

DOMUSPLUS: Regarding the thermal insulation, I don’t think there is much space left 4 energy efficiency improvement in our buildings. Our calculations confirmed that there is no use for additional thermal insulation and thicker building fabric because the cost outgrows the benefits. Standard wall we are offering is 38 centimeters out of which 35 is thermal insulation. Thickening the insulation increases cost while energy consumption reduction isn’t equivalent. here is the spot where building technical systems as heat recovery or heat pumps significantly improve building energy balance.  

BIMCERT: External envelope is maximized regarding the heat retention. you are using the technical systems to further reduce the energy consumption. Would it be interesting to try to reduce the insulation to reduce production costs and life cycle costs of the building?

DOMUSPLUS: I believe this is suitable for larger buildings. Changing the production processes on single family houses isn’t financially acceptable. We tried out and simulated other construction materials which might reduce the wall thickness and increase the usable building area but abandoned the further research because of unavailability of materials.

BIMCERT: How did you organize worker training and transition to BIM during the BIM implementation in the company?  

DOMUSPLUS: Initially we organized archi CAD training in duration of 60 hours, which actually took twenty 3-hour lectures, depending on worker and time availability. We are developing templates for our houses (building fabric) which will be applied to all our projects from the beginning of next year. factory Production part of the company was also supplied the education in machine handling because they don’t have too intense contact with BIM – they have to receive the file and be able to apply it on the machine, read it and input required materials for that building.

BIMCERT: Standard finish level you are offering is high “roh-bau”. Are you including additional finishing and if so are you doing that with your own personnel?  

DOMUSPLUS: We have multiple demands for higher completion level, and as a standard, now we offer electrical installation and if requested heating and mechanical ventilation with heat recovery. Finishing works are dependent all the agreements with investor. We employ subcontractors for finishing works.  

BIMCERT: Do the subcontractors require exchange of digital information or request BIM?

DOMUSPLUS: Generally, subcontractors don’t, but designers do. we just had a meeting with mechanical engineers who are also implementing BIM and we have to work in close cooperation. They are using Revit, So, it would be good that we define penetrations through walls, beams for ventilation, other mechanical systems, and prepare for that in factory production of building components. That way we will have less interventions on the field breaches of weather proofing and vapor barriers. as we are not designing the mechanical systems ourselves, there are still adjustments with mechanical and electrical engineers. Mechanical engineers, as I see it, will soon implement BIM, electrical engineers and others a bit slower. Part of the envelope problems has been solved on our side by implementing the installation layer inside the vapor barrier, so we can close the external envelope without the installation breaches. Basements and footing builders are still far from BIM implementation.  

BIMCERT: You seem to be specific in Bing implementation because your buildings a modular product which can be very well coordinated through BIM, but interface of the building to the footing and final works are still open ended – I would say traditional?

DOMUSPLUS: Unfortunately, we haven’t yet met the contractor prepared to work the other way. large construction companies and large projects have BIM as mandatory condition. our product is single family home – we can make it without it, but we are trying to implement BIM in time and get ready for the change.

BIMCERT: When organizing the education in the office, how did the workers react to it? 60 hours is a significant time considering the workload and private life? how much of their own time were the workers ready to invest in learning?

DOMUSPLUS: Exactly. Decision on training in work time or free time is always hard. Spirits were divided by half – half of the team we’re more inclined to do the training in their free time, and the other half wanted to do it during the working hours. Finally, majority agreed on training on Friday before closing time. I’m informed that everybody used additional training options in their free time – YouTube videos, tutorials, online examples and other informal education which we sometimes don’t track and don’t consider the education, but at the end of the day everybody is using new tools.

BIMCERT: Thank you for the conversation and insight in your BIM implementation

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