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Thermal Mass in Buildings

Posted January 12th, 2011 in building science by TitanWall

Happy New Year to all our readers.  2011 is gearing up to be a good year for TitanWall, with some really great projects getting started and some others wrapping up.  Be sure to sign up for our RSS feed to get the latest updates and news from us as we showcase these projects.

Today, I’m going to continue the series on thermal performance of buildings with a discussion of thermal mass.

Background

Thermal mass describes when the mass of a building or material aids in protecting the indoor environment from temperature fluctuations. For example, as the outdoor temperature changes throughout the day, a building designed with a large thermal mass inside the building envelope helps to mellow the daily temperature fluctuations felt inside the building. This is because the thermal mass absorbs the heat when the surrounding air is hotter than the mass, and releases it when the air around it is cooler. This is a very different material characteristic than thermal resistance but as I mentioned in a previous post, it works in combination with insulation to create a more comfortable and energy efficient building design.

Technical Info

Thermal mass is often called thermal capacitance in scientific circles and it is defined as the ability of a body to store heat (lots of good information on wikipedia). It is usually shown as the symbol Cth. It is measured in Joules per Degree Celsius (J/°C).

In Thermodynamics, thermal capacitance is governed by a simple equation:

Q = CthT

Where Q is the heat energy transferred to the body, Cth is the thermal capacitance, and ∆T is the change in temperature the body undergoes.

Essentially, if 500 J of heat energy was applied to a material with a thermal mass of 40 J/°C it’s temperature would rise by 12.5 °C.

Similarly, if a material with the same thermal mass cooled by 12.5 °C, it would release 500 J of heat energy to its surroundings.

What this all means

Ok, enough geeking out already. The bottom line is that, if done properly, adding thermal mass to a building can significantly increase comfort and thermal performance, resulting in lower operating costs with minimal capital investment. Saving money and being green is a win-win option!

Using Thermal Mass Effectively

To be effective, thermal mass must be combined with a controllable energy source when integrated into a building design. There are two major ways of accomplishing this, either through good passive solar design, or using active energy systems to transfer heat to and from the material with a high thermal mass. Thermal mass works best when optimized for both passive and active applications.

The best materials for thermal mass have a high specific heat capacity, a measure of the change in temperature of a specific mass of material as heat energy is absorbed or released. The other characteristic of good thermal mass materials is a high density.

Every material has a thermal mass, although some have more than others. Here is a table from a Canadian blogger showing the thermal mass of various materials. He didn’t cite references, so the data may be inaccurate, but it seems inline with other charts I’ve stumbled upon. Feel free to correct the numbers if you feel they are misleading. I’ve added TitanBoard’s specs to the list for comparison.

Material Heat Capacity
(J/gK)
Density
(kg/m3)
Heat per volume
(MJ/m3K)
Water 4.18 1000 4.18
Gypsum 1.09 1602 1.746
Air 1.0035 1.204 0.0012
Concrete 0.88 2371 2.086
Brick 0.84 2301 2.018
Limestone 0.84 2611 2.193
Basalt 0.84 3011 2.529
Sand (dry) 0.835 1602 1.337
Soil 0.80 1522 1.217
Granite 0.79 2691 2.125
Wood 0.42 550 0.231
TitanBoard 1.85 1100 2.035

As can be seen, TitanBoard’s thermal mass characteristics compare favourably to other materials, with its capacity on a per volume basis just shy of concrete. This means that TitanBoard, our proprietary sheeting for our panels, can contribute to the thermal mass of buildings designed with TitanWall panels. The thing to keep in mind though, is TitanBoard is only 12.5 mm thick, so in terms of volume compared with, say concrete slab floors, it is only a secondary contributor, nonetheless, we have anecdotal evidence of significant thermal mass contributions from TitanWall panels and are developing some controlled testing to better understand this important effect.

Climatic influences

Thermal mass strategy for cold climates.
(courtesy Australian Government)

The strategies used to design buildings with thermal mass vary depending on climate conditions at the building site. In our part of Canada, we spend a large part of the year heating our buildings, so thermal mass is best placed where heat energy from the sun can be absorbed readily during daytime hours and be radiated back into rooms at night.

Thermal mass strategy for hot climates with large
diurnal temperature variation.
(courtesy Australian Government)

In hotter climes with large daily temperature variations, a different strategy can be employed where the thermal mass is acting primarily to buffer cooling energy inputs, acting as a sink for excess heat during the day and taking advantage of the cooler nights to release that excess heat again with good ventilation.

On a final note, some building materials have hit the scene recently that take advantage of the significantly larger heat capacity of materials as they change from one phase of matter to another, ie. from liquid to solid or vice versa. These materials are known as phase change materials and can achieve similar results to traditional thermally massive materials, with much less mass. I don’t have much experience with them, but perhaps you do. I look forward to your comments and hope to learn something new.

Happy Building!

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Thermal Performance of Building Envelopes

Posted December 22nd, 2010 in building science by TitanWall
Thermographic Image of TitanWall Research Facility
Courtesy Prof. Tang Lee

Hello everyone. Today we continue our series on the building envelope with a discussion of thermal performance, one of the key factors in determining the comfort of the indoor environment and the energy efficiency of a building.

These days every home builder and construction material salesperson you talk to will spout off terms like “R-value,” “U-value,” and “thermal mass” in an effort to make you believe that their product is not going to cost you a fortune in heating bills and ensure a comfy space. We’re no exception at TitanWall, but hopefully by the end of this series, we’ll help you understand a bit better what these terms really mean. In addition, we want to give you an understanding of the bigger picture — of how the thermal performance of your envelope can interact with other systems in your building to provide options for more efficient and cost effective design.
Its hard to believe that just over a century ago buildings were rarely insulated at all. Central heating wasn’t common until the 1800’s and fibreglass insulation wasn’t even around until the 1930’s. How quickly things have changed! Now there are so many different materials and methods to choose from, it can be overwhelming to try and figure out what will work best for your project. From fibreglass batts, to spray foam, to blown in cellulose or our favorite, MgO insulated panel systems, there are more choices becoming available almost every week as new innovations are brought into the marketplace.
So why is thermal performance important? For Canada, in 2008, 60% of all commercial energy consumption and 82% of all residential energy consumption was for space conditioning and water heating, according to Natural Resources Canada. By increasing the thermal performance of a building envelope, there is an opportunity to significantly reduce the heating energy use of a building. This often has the biggest ROI for any green building investment.
There are several factors that affect the thermal performance of a building:

  • thermal resistance
  • thermal mass
  • air permeability
  • building orientation and form
  • mechanical system design
For an effective thermal strategy for your building, all of these factors must be addressed together, and we will try to do so in this series, but for today’s post, we’re going to takle factor number 1, thermal resistance.

Thermal Resistance:

Thermal Resistance is the degree to which a material resists heat flow through itself. It is the opposite of thermal conductivity, or the degree a material conducts heat. There are several measures of thermal resistance including RSI (SI units) and R-value (imperial units). For all you geeks out there like me, RSI is measured in Kelvin square meters per Watt (K m^2/W) and R value is measured in square feet degrees fahrenheit hours per british thermal unit (ft^2 ºF h / Btu). They are easily confused but also easily converted: 1 RSI = 5.68 R.

The important thing to remember about thermal resistance is that the higher the value, the better insulated your wall is.
Wikipedia has a great chart of R and RSI values per inch of various materials. From the chart you can see that EPS, like what we use in our panels ranges from R 3.85 to 4.2 per inch, depending on density. Although there are other materials that have higher values, if we were to look at cost and environmental footprint as well as r-value, EPS is one of the best choices.
A wall isn’t just comprised of highly insulative materials though; it has other components that need to be taken into account when thinking about thermal resistance. Things like studs, bolts, plates, sheathing and anything else in your wall. Depending on the make up of these wall components and their thermal resistivity, a wall can have a true R-value significantly lower than the R-value of the insulation. This is due to a concept known as thermal bridging.

Thermal bridging is when a material with a lower R-value provides a conduit for heat to flow faster through a material of higher R-value, thereby lowering the total thermal resistance of the assembly. In a typical stud wall, up to 25% of the wall area is comprised of wood studs, with an R-value of about 1 per inch.
This can cut the R-value of a wall by more than a third in some cases. Windows also can contribute to lower r-values so it is important to select the most efficient windows your budget will allow.
Another material characteristic that affects your wall assembly is that of thermal mass. Be sure to subscribe to our feed to you can see our next update where we’ll explain the benefits of thermal mass in building materials.
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The Building Envelope

Posted November 26th, 2010 in building science by TitanWall

A lot of people ask us “What makes TitanWall so great? Is it really any better than a conventional framed exterior wall system?”

The building envelope
Well, we certainly think it is and here’s why — it all boils down to what you want in a building envelope.
The building envelope consists of all the roofs, walls, windows, doors and foundations that enclose the indoor environment of a building. It is a complex system that performs a variety of functions including ensuring structural integrity, controlling moisture, preventing thermal leakage and controlling air pressure boundaries.
Canada Mortgage and Housing Corporation (CMHC) has a great page of articles on the building envelope, highlighting best practices in many different aspects of building envelope design.
Obviously, there are many details required for an effective building envelope. These details get even more complicated when trying to build an environmentally responsible, energy efficient building due to the increased need for air-tightness and thermal performance. And then, of course, there is the need for a different evaluation of what materials are deemed acceptable for use according to the principles of the project or any green building rating systems used.
Over the next few weeks, we are going to post a series of articles on the building envelope and show our readers how the TitanWall MgO insulated panel system can provide an extremely effective building envelope solution in a variety of applications. If there are any questions you have or requests for specific posts on building envelope topics, please ask them in the comments section of our blog and we will answer them with the help of our resident building science expert, Professor Tang Lee of the University of Calgary.
Our first post will be on the topic of thermal performance in building envelopes, so get your questions ready and send them over early and maybe we can get them into the original post.
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TitanWall Garage Construction

Posted November 25th, 2010 in Videos by TitanWall
Check out this great video of a TitanWall Custom Garage going up!
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Edmonton Eco-Plex

Posted November 18th, 2010 in Feature Projects by TitanWall

10920 123rd St

Rendering of Eco-Plex


The Eco-Plex is an up / down duplex in Edmonton’s Westmount community.
The goal of this project is to provide a multifamily dwelling, which meets the needs of the client for an accessible, durable, energy efficient house on a budget. The home uses the latest envelope and mechanical technologies and has features that will allow it to improve its ecological footprint as new technologies like photovoltaics become more economical.

Envelope Design:
The envelope is completely made of TitanWall MgO insulated panels. The structure consists of 4’ TitanWall frost walls for the crawl space (on strip footings), a TitanWall floor, 8 1/4” TitanWall wall panels on the main, second and third floor and a 10 1/2” TitanWall roof. The thicker-than-normal walls provide an insulation value of R-30 while the roof boasts R-40. An advantage of using TitanWall SIPs is a more consistent layer of insulation throughout the whole wall, roof or floor; compared to standard stick frame construction, thereby reducing thermal bridging. TitanWall construction also ensures a tighter seal for the envelope, reducing air leakage and increasing energy efficiency.


Mechanical Design:
The mechanical system was designed to be compact yet effective. The whole system consists of a heat recovery ventilator (HRV) and a combination on-demand boiler (for domestic hot water and heating) coupled with radiant in-floor heating. The HRV provides fresh air and circulation while the boiler provides heating. A 2 1/2 – 3” concrete topping was added to the radiant in-floor loops on each level to provide thermal mass that stores excess energy from the sun and the in-floor loops.


Key Stats:

  • 1500 sq. ft. per unit
  • $170/sq. ft. cost to build
  • Yearly heating costs estimated at $400/year
  • Vaulted Ceilings allow for better use of space
  • Low-e, double glazed All Weather Windows
  • Designed to meet EnerGuide 89 Standard
  • Solar-ready



More Images:


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House Photos

Posted November 1st, 2010 in Photos by TitanWall

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Magnesium Oxide Wallboard

Posted November 1st, 2010 in building science by GOMGO

Information below has been copied for your convenience from Wikipedia.

Magnesium oxide is a versatile material used in residential and commercial building construction. It is suitable for a wide range of general building board usages and for applications requiring a fire rating as well as mold and mildew control as well as sound control applications.

As an environmentally friendly building material, magnesium oxide board has several attractive characteristics: fire resistance, moisture resistance, mold and mildew resistance, and strength derived from strong bonding between magnesium and oxygen in magnesium oxide (MgO; pronounced: em, gee, oh). Magnesium oxide boards are used in the place of the traditional gypsum drywall as wall and ceiling cover material or sheathing. It is also being used in a number of other construction applications such as: fascias, soffits, shaft-liner & area separation wall sheathing, and as tile backing (backer board) or substrates for coatings and insulated systems such as Direct-Applied Finish Systems, EIFS, and stucco.

MgO board for building construction is available is various sizes and thickness. It is a non-paper-covered material and generally light gray, white or beige in color. It comes in various grades, such as smooth finishes, rough textures, and utility grades.

Presently MgO board is widely used in Asia as a primary construction material. It was designated as the ‘official’ construction specified material of the 2008 Summer Olympic Games and was used in extensively on the inside and outside of all the walls, fireproofing beams, and as the sub-floor sheathing in the world’s tallest building, Taipei 101, located in Taipei, Taiwan.

MgO is manufactured in a number of areas around the world, primarily near areas where MgO ore (periclase) deposits are mined. Major deposits are found in China, Europe, and Canada.[1] MgO ore deposits in the US are negligible. Estimates put the use of MgO board products at 8 million SQF in Asia alone. It is gaining popularity in the US, particularly near coastal regions.

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Welcome

Posted October 29th, 2010 in Uncategorized by TitanWall

Welcome to the blog for TitanWall Building Systems.  We will updating this page with lots of news, photos, information and discussions about building with our products.  We look forward to your input.