Thoughts on the Engineering Industry

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Archive for the tag “house”

Design Issues for an Affordable DIY Tornado Shelter

Hello everyone. I hope y’all are doing well.  I’ve been taking some time to plan my move to the new job and be as ready as possible for the new job.  Today, I would like discuss the design of affordable DIY tornado shelters.  For reference, I will use a rough description of a study performed by Research Engineer Bob Falk of Forest Products Laboratory in Madison, WI. (http://goo.gl/qRM87t)

Tornadoes have always been a risk for people living in the midwest; and as a result, the design of wind and debri resistant structures has always been part of the house construction conversation.  There have been more technical and more resource intensive design/construction ideas discussed before.  However, the reason I chose to do a blog post using this source is because the goal is a design that can resist 250 mph winds and debri using only affordable wood and construction methods.  Additionally, the construction process is to be something that uses only basic construction skills.  I really like this concept not because this is the perfect solution, but because this is good starting point for people to be reasonably safe.  The design is constructed using interlocking timber with plywood overlay and the wood structure is connected to a concrete foundation using bolts.  The door is still designed using steel; however, Falk is researching a way to use a wood door.  The structure is currently undergoing testing using 2 x 4’s shot at 250 mph.

I believe that this would be a good design/construction process once the following issues have been addressed:

A repeatable design plan:

Whatever this design may entail, there needs to be an empirical, repeatable process that can be easily designed and built.  A good plan should include the following at minimum: door frame requirements, bolt spacing requirements along the wall, nail spacing requirements along the plywood and interlocking timber sections, timber grading requirements, concrete foundation requirements, and roof connection requirements.

Design Study of the Door and Frame:

As far as wind is concerned, one critical issue is the door and the frame around the door.  And especially after reading this article, it came to my attention because nothing is mentioned about the study of the frame.  The design uses a steel door, so the door shouldn’t be the issue in that case.  However, if the frame can’t resist the winds in the the hinge and bolt system and the wall/frame connection around the door the door system, it will fail to resist the loads.  Some basic wind tunnel testing should be a good starting point.

Bolt Connection to the Foundation:

The walls shouldn’t be the critical part of the wall if this is constructed as it says.  Yes, would splinters and could be dangerous; however, if the testing is occurring as described and enough strength is provided based on these studies the walls shouldn’t splinter.  However, there will be some very high shear and moment loads on the bolts.  If not adequately tested and designed, the wall could break of along the foundation.  I would argue that this even more critical as well since it would affect a whole section of wall, so I believe details need to be examined here.

Roof Connection and Design:

With the increased wind, the uplift forces on this structure will be very high.  Furthermore, I believe this has to be designed as an independent structure as well as a structure that is part of a larger building.  With this in mind, uplift forces applied to the whole structure of the second floor or roof needs to be considered as well.  Connections at the top of the wall need to be able to resist that full load or design needs to allow for relief of those forces if the house breaks around the shelter.  Either way, study and wind tunnel tests are required for a safe design.

What is your opinion on the shelter mentioned in the article?  Do you agree my assessment of the design?  Is there anything I missed?  Please share this post if you enjoyed it and have a good week!

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The Application of Biologically Grown Materials to Building Design

Hello everyone, I hope y’all had good weekend.  Today, I want to talk about some new building materials being researched that are biological produced in a replicable process.  One of the common characteristics is that these materials will involve bacteria or something else derived from organisms.  The fact that these materials don’t require significant carbon output is one major benefit.  Another benefit for most of these materials is that they are actively reproduced over time once they are installed as well.  The building materials are described below with some insight on possible benefits and issues.

bioMason Brickshttp://goo.gl/PY68HQ

The bioMason brick is a brick of sand and cementitious material in which the cementitious material is created using a bacteria.  The brick mixture is created and over the course of 5 days the bacteria solidifies into a coral type material with the strength of a normal brick.  The major benefit for this innovation is that it doesn’t require the heat and raw materials used in creating normal bricks; this reduces the cost of the brick by 40%.  They are currently conducting experiments to research bacteria creation using the following materials: urea, salt and yeast extracts, and seawater.

I see this having one major benefit – it would not significantly change the design and build process for masonry.  Masonry strength is mostly determined by the strength of the mortar as long as the masonry unit strength doesn’t change significantly.  The benefits of the bioMason bricks combined with the low technology change requirement makes this much more effective.

Mushroom Insulation Materialhttp://goo.gl/SZcfA

This is a stiff insulation material using plant stalks and husks combined with Mycelium.  There are two forms of application being tested currently: growth inside the wall and spray on insulation.  The insulation is fire resistant and fully compostable.  Additionally, it does not contain formaldehyde or any other harmful organic materials.  This same material can also be used as compostable packaging material.

There are several benefits to this material.  Like before there is no significant change to the other building processes related to it.  It also has great applications outside of this usage alone and is completely compostable once it is not needed anymore.  The only drawback I can potentially see is there being an organic material harmful to humans that is unknown as of yet – similar to what happened with Asbestos. It has great potential overall though – it is my recommendation that more health testing be done before large scale usage.

Self Repairing Concrete:

Research is being conducted on a bacteria that can be used to repair concrete as it ages.  Bacteria engineered to thrive in dry climates is being created to be placed in the concrete mixture.  The bacteria would release Calcium Carbonate as part of the waste process which would fill the holes and cracks over time.

There is one possible major benefit I see – the reduction in maintenance required for the concrete designed this way.  However, more research would be required to determine it’s efficiency.  Additionally, nothing is mentioned about resources and energy required to produce this bacteria; if it requires a high amount of energy and time/raw material resources, it may become impractical to use.  I might also add that the issue of infection might come up here as well; but if the claim is true that it is bacteria that thrives in dry climates, the danger to living organisms would be greatly reduced.

What is your opinion on these possible advancements?  Can you see them being used in the future?  Thank you for your time and have a good week!

Reference:

Wollenhaupt, Gary,”Self-Repairing Concrete Could be the Future of Green Building”, Forbes Online, January 6, 2014, http://goo.gl/IRyzHi

High Performance Energy Saving Design for the Karuna House – Window/Door Design

Passive House Green Home Building Tips: Karuna House Windows & Doors

Hello everyone! Today I would like to go back to my series of posts outlining the design and construction of the Karuna House.  The topic for this post will be the selection and resulting benefits of the improved windows and doors.  Windows and doors are the biggest holes in the building envelope above ground.  These innovations are what allow the HVAC systems to reach their maximum efficiency.  Additionally, windows and doors are also a major aesthetic concern and these aesthetic factors play a big role in the decision process.

The Karuna House uses triple glazed, high solar heat gain, R-8 windows with a very thin frame.  This type of window has an increased level of heat gain, but significantly improves the building envelope by allowing additional insulation to be placed around the frame.  The triple glazed window also has a well documented performance history because it has been in use since the 70’s in Scandinavia.  For the exterior doors, the Karuna House uses Optiwin doors.  These doors are thick with insulation in the middle and airtight with multi-locking mechanisms to ensure a tight seal.  To help with the heat gain issue for the windows, a shading system that can be lowered over the windows was installed.  This has an additional benefit of being modern and aesthetically appealing.  The triple glazing also provides a very clear view through the glass which adds to the modern, aesthetic appeal.  To further improve indoor conditions, these windows and doors increase comfort by reducing the draft found near the window and door openings.  All of the benefits above combine to reduce the impact on the mechanical systems which allows for a simpler, more efficient system to be used.

Overall these systems are simple and nothing too complex.  However, these systems apply the same philosophy that is applied to the building envelope in general – simple and efficient solutions to problems.  Furthermore, the philosophy applied to the building envelope, windows, and doors altogether should reap a lot of benefits for the mechanical systems and the energy usage correlated to that.  The take away here is very similar to the previous post on the Karuna House – a little a effort put into finding cost efficient improvements to small elements of the house can improve the overall efficiency a lot.

What do you think about the window and door improvements on the Karuna House?  Are there any issues that need to be addressed or  improvements that can be made?  Thanks for your time and have a good week!

Resource:

Hammer & Hand,”Karuna House: Windows and Doors”, http://goo.gl/j7zAAy

High Performance Energy Saving Design for the Karuna House – Wall System

Passive House Green Home Building Tips: Karuna House Wall Assembly

Hello everyone.  I hope your weekend went well.  Everything is picking up for me again – my day job and school included.  Not in a stressful way though; it feels good to be doing some productive stuff again.  Today, I want share the second part of my series of post describing the design of the Karuna House and the topic this time around will be the wall system.

As stated in the article, the main issues in designing the wall were moisture, heat and air control.  Along with that, this design added the other standard of being able to release moisture once it entered the system as well.  With that in mind, the main goal of the wall design was to create a building envelope that was air tight, water tight, vapor permeable and super insulated.  On the inside of the wall, standard natural lime coating and dry wall were used for interior design purposes.  Beneath that, a stud frame of engineered wood members was built to support the wall structure and was insulated with high density cellulose.   The high density cellulose consisted of recycled newspaper and naturally buffered against moisture which improved the walls durability.  After that, there was the air barrier which prevented air from flowing through the wall and allowed the insulation to perform at a much higher level.  The air barrier was created using plywood coated with vapor permeable liquid applied membrane.  After that level, a frame of Z Joists with foil faced Polyiso Foam was placed over that.  This element was the critical part of the design in regards to performance and durability.  The final element was the rain screen system made out of cedar siding placed 1 inch off of the Polyiso Foam.  Window frames were sealed using Joint Seam Filler and Fast Flash around the window structure.  Details aren’t provided about door frames but it would be a reasonable assumption that they did the same thing there as well.

In my opinion, the design of the wall framing system isn’t as unique as the foundation system.  It has been standard practice for a while to use foam insulation and air barriers.  The same goes for the window sealant process.  However, the attention to detail in what to use and how to apply it is still a good take away for building design in the future.

What is your opinion on the wall frame system?  Is there any improvement they could have made that would have increased energy efficiency?  Thanks for your time and have a good week! 🙂

Source:

Hammer and Hand, “The Karuna House: Wall Assembly”, http://goo.gl/sHU7kv

High Performance Energy Saving Design for the Karuna House Part 1 – Foundation Design

     Hello everyone! I hope your holiday break went well.  I had a fun time with my family and definitely felt like I recharged my batteries as well. Hopefully you guys could do the same.  Today I want to start a series of blog posts on a detailed overview of the high performance systems used in the Karuna House created by Holst Architecture and Hammer & Hand.

The Karuna House is a house designed to meet Passive House standards, Minergie-P-ECO, and Platinum LEED Home Standards.  The client is a leading proponent of high performance design technology for climate control.  This house is intended to be a case study in the usage of the current technology on the market today.  In the first part of this blog post series, I am going to discuss the design of the foundation and the energy saving technology applied in that part of the design.

The main concern for the foundation involved insulating the basement and foundation.  With that in mind, most of the technology focuses on maintaining a good quality building envelope that insulates well.  The first step was the cut and fill for the excavation.  In this step, the cut was balanced with the fill to ensure that there wasn’t a need to haul around aggregate to complete the fill process.  For the next step, an Expanded Polystyrene (EPS) geofoam foundation insulation was placed around the cut and fill earthwork before the concrete foundation was constructed.  Next, the footings beneath the structure were placed and a moisture blocking capillery break material was placed on top of that.  Once the footings were in place, gravel fill was placed for the foundation base and the basement foundation wall was constructed with a vapor barrier extending to both sides of the wall.  The concrete mix used in the basement foundation wall consisted of 30% fly ash and used locally sourced aggregate.  In order to obtain better energy efficiency, EPS was placed in critical thermal bridge sections.  Along the foundation walls, a product called a drain board was applied to it’s surface as well to allow water to flow down the foundation walls and past the footings.  Once all that was completed, they applied the vapor barrier over the gravel base and laid some more EPS foam before they constructed the slab portion of the foundation.

My take away from reading the article and watching the videos is that there are two critical issues that affect house foundations – moisture control and thermal bridging.  The designers used the EPS and vapor barriers to address these issues.  Along with that, methods of construction were used that reduce the use of energy/material in construction as well.  Overall, I think this was a good application of some practical design ideas.  A lot of designs like this get caught up in following the latest complex and cool looking trend instead of finding a solid and fundamental solution to the problem – this design avoids that fairly well.

What are your thoughts on the design?  Does it seem like a practical application to use for increased energy efficiency?  Any issues you worry about over it’s life cycle?  Thanks for your time and have a good week! 🙂

Source:

Hammer and Hand, “The Karuna House: Foundation System”, http://goo.gl/C9Hccu

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