Outdated Info

First post in a long time, and unfortunately it's not because of any new and exciting developments, but rather that I finally got around to take a look at this blog and realized that I was hosting some outdated preliminary findings under the "How" and "Why" sections at the top. Since I don't currently have time to update these I've resorted to simply taking them down for the time being.  For people seeking information on the concept I recommend looking at the thesis paper that is still available in an earlier blog post:

Cross Ventilation Heat Recovery Concept

Since this blog is still getting traffic (from what I naively hope is relevant industry people, not bots), I thought I would share another ventilation concept that is similar to the StackHR concept in that it utilizes hollow core slabs and provides heat recovery and preheating of the ventilation air. All credit for the idea goes to my dad who came up with the concept when I pitched the original StackHR concept for him. I have sketched the concept below: If it isn’t completely clear what’s going on from the sketch here comes an explanation: Half of the hollow core concrete slab cavities are open to the windward side of building, other half are open to leeward side. Openings are provided between the cavities and the ventilated space opposite of  thefacade opening. Air enters building on windward side, passes through slab, enters ventilates space on leeward side, passes through ventilated space, exits ventilated space on windward side, passes through slab, exits building on le

Invention entered public domain

Today it is one year since I filed a provisional patent application for the StackHR concept. As I have chosen not to follow that up with a non-provisional patent, the idea has now entered the public domain as of today. I probably won't be able to find time to make a publishable article on the subject any time soon, and I think the same goes for professor Zhang, who has, however, told me that he will keep it ready in the drawer. It is my hope that somebody will come across this blog and pick up the idea, and develop it to the point where it can find real world applications. Now the idea is at least free for anyone to use however they might want.

Research paper

It's been a while since my last post, but that doesn't mean that nothing has happened. I defended my thesis in late April, and luckily the panel seemed veryv impressed with my work, and had only minor remarks and comments for corrections. I was, therefore, awarded a grade of 12 (highest possible grade in Denmark). I am currently working with my supervisor, professor Zhan, on a possible release of the work as a research article in a scientific journal. With the both of us being busy with other work right now, it might be a while before this actually becomes a reality though. I will make sure to keep you posted on here.

Final Thesis Report

Here is the finished report. The thesis defense is taking place on the 29th of March at Navitas in Aarhus, Denmark. If you are interested in attending the defense or would like a copy of the appendix just send me an email ( 

First results from experimental setup

With all of my classes and finals being over I'm now able to focus my attention on the StackHR project and writing my thesis. I have been making a lot of progress on the project lately, so I think it's high time for a little update here on my blog! For the thesis I'm focusing my attention on the heat recovery performance when operating at laminar and transitional flow conditions. The setup basically consists of the coaxial heat exchanger "ventilating" a "room" that is represented by two plenum boxes. The two boxes are connected with a duct, through which I'm moving air with a couple of small PID controlled desktop computer fans. The fan speed is varied so that a pressure differential between the two boxes, equal to what would naturally occur due to stack effect in a full size setup is maintain at all times. Below are a couple of pictures of the actual setup: I have already gathered a bunch of data, and I have been really s

First Public Release of Research Paper on Sustainability of the StackHR System

Here is the paper that Nikolaj and I wrote about our Life Cycle Assessment of the StackHR system for our class on Sustainable Design and Production at Aarhus University. Be warned that it does get a bit technical in places. I hope you enjoy the read if you still choose to proceed!

Life-Cycle Assessment of StackHR

Alongside my experimental testing of the StackHR concept for my masters thesis, my buddy (and fellow postgraduate engineering student) Nikolaj Vendelbo and I have been working on a LCA study investigating the sustainability of the concept for quite a while now. Today we presented our findings for our class on Sustainable Design and Production at Aarhus University, and apparently we must have done quite well as we got some great feedback from both of the professors attending the presentation. For our study we investigated the sustainability of the StackHR concept through a comparative LCA where we benchmarked the proposed system against both traditional natural ventilation systems and State-of-the-Art mechanical ventilation systems featuring high efficiency heat recovery. We did so by evaluating the total environmental impact of the systems in terms of greenhouse warming potential (as well as other relevant impact factors) over the full expected lifetime of a building. Doing so obvi

Sensirion SDP810 Differential Pressure Sensor Code for Arduino

Lately I have been working a lot on a control system to emulate stack effect for use in the experimental setup I'm constructing. For the control system I'm using some small but extremely accurate and fast responding digital pressure differential sensors manufactured by Sensirion. The sensors are called SDP-810-125Pa, and while I've found two Arduino libraries intended for communication with these sensors, neither worked for what I'm doing, as I need to run the sensors in "continuous mode". I've therefore resorted to just communicating directly with the sensors over I2C using the build-in Arduino Wire.h library. This has turned out to not be too difficult (I managed it after all), and the Arduino code can still be kept pretty compact. I'm sharing the basic code below for anybody else using these sensors with Arduino MCU's. Also I've been in contact with a software developer at Sensirion who has told me that he is working on expanding their ardui

Construction has begun

Besides calculating and coding the best I've learned, actual construction of the test setup has now also begun. Luckily I have a dad with experience from the trades willing to lend me a hand.