Fin MacDonald

Information on me and my current projects

Category Archives: Industry Tools

Geographic Information Systems applied to LEED and Beyond

Geographic Information Systems (GIS) are databases that contain geographical information. The leading GIS software is ArcGIS by ESRI. In the past months I have been exposed to both the software, and its uses in the green building industry. I had a chance to talk with some ESRI representatives at Greenbuild this year in Toronto. GIS has much to contribute to LEED and other rating systems as the industry builds momentum.

Maps can be used to assess the public transportation of a building, as well as the community connectivity and relative distance to other building types. ArcGIS also creates a geodatabase that the map is based on, and this can contain all sorts of useful data for analysis.

A buildings layer that is added to a map can contain a table of values with a row for each building drawn on the map. The tables can contain all sorts of data about the building. LEED points earned, the level of certification achieved, and the architects and engineers on the project are examples of useful data that could be stored. A detailed geodatabase could help future developers decide which LEED points to pursue based on a proposed buildings location.

ArcGIS can also create beautiful maps. I’ve created one as an example using the publicly available list of LEED projects in the Halifax, Nova Scotia, Canada area. This list is available on the website of the Canadian Green Building Council (CaGBC). I’ve uploaded the map below.

Green Buildings in Halifax



Blower Door

I have recently been getting some experience using a blower door. This is a device that is used to measure the amount of air infiltration in a building. The amount of air changes per hour that occur because of air passing through cracks in the buildings envelope has a big impact on the energy used for heating and cooling. Air leaks generally occur at the seams around windows, doors, and other holes. An R2000 home should have less than 1.5 ACH (air changes per hour) while a passive house sets its standard at 0.6 ACH.

The blower door connects to an exterior door frame of the building and covers the entire opening. It uses a large fan to create a pressure difference of 50 pascals between the interior and the exterior. Once the pressure difference is in place you can check for leaks in the building envelope by using smoke. If you see smoke being drawn through the envelope you mark the area and come back and seal it better after the test.

I recently took part in a blower door test for a passive house. Since 0.6 ACH is so low and hard to achieve the builder had a preliminary blower door test done early in the construction process to identify problem areas while they could still be fixed. Often blower door tests are done at the end of the construction when it is too late to fix problems, and I was impressed with the extra steps being taken to ensure efficiency.

The blower door I used is called the Minneapolis Blower Door and is manufactured by the Energy Conservatory.

Blower door set up on a passive house

Solar Pathfinder vs Solmetric iPV

Today I conducted a little test to compare the performance of two low cost solar site assessment tools. I consider low cost to be anything under $1,000. These tools provide infomation about the amount of available sunlight that falls on a surface. They do this by examining the landscape features in the area that provide shade at different parts of the day such as buildings and trees. These tools provide a percentage of available solar radiation you can expect to receive. This can then be combined with weather data and solar panel information to perform preliminary energy calculations using energy modelling software. This site assessment information is supplied for each month however for the purpose of this test I am only going to compare the total annual values.

The two tools I compared are:

1) Solar Pathfinder ( $299 + $199 software

Solar pathfinder image. The black areas inside the ring mark the obstructions in the surrounding area. This image is traced using computer software.

2) Solmetric iPV iPhone application ( $29.99

The Solmetric app lets you trace the obstructions directly with the iphone.

The calculations for the percentage of available sunlight were as follows:

Solar Pathfinder: 84%
Solmetric iPV: 86%

Both of these tools require tracing so they have a element of human error involved. When using the pathfinder you take a picture of the equipment and trace it using the computer software. When using the Solmetric app you trace the horizon directly with the iphone. Given the close proximity of the results I don’t really feel as though one is any better than the other from a performance standpoint. When you consider the price the Solmetric iPV iPhone application is the clear winner, but only if you already own an iPhone.

Solmetric also makes professional site assessment tools in the $2,000 price range that do not require any manual tracing and are remarkably accurate.

The Web Energy Logger (WEL)

The WEL is a low cost but effective data logger that can be used to monitor energy use or generation. It contains a one wire bus that allows digital sensors to be strung along like christmas tree lights. It also contains 6 pulse inputs, 8 run inputs, and 2 4-20 mA analog inputs. Pulse sensors return an electronic pulse signal and applications may include paddlewheel flow meters for water flow. The digital pulses can be counted and converted into a volume flow rate. Run sensors tell you if the device connected is on or not. Current switches can be installed over power cables to current and return an on/off signal. 4-20 mA sensors send a mA current signal that can be scaled into engineering units.

Inside the WEL you are allowed 150 variables. These can be sensor inputs, constants, or simple expressions of other variables. The WEL has limited internal memory so it is limited to simple 2 variable expressions and is not capable of doing exponents or square roots. That being said most energy calculations can still be performed inside the WEL. It also has support built in to maintain running totals for the day, month, or year of any variable.

The WEL uses a rabbit board network chip to connect to the internet and transmit the data. It can be set to log data at any frequency, entered in minutes. By default it connects to the WELserver ( This webpage contains a map of the world with all the other WEL’s shown on it. It is a great tool because it allows you to not only monitor your system, but see how others are doing as well. With some ingenuity you can connect the WEL to your own server to record and present the data there. The WEL posts data that can be received by a simple CGI or PHP script.

Typical WEL applications include monitoring of geothermal, solar thermal, solar photovoltaic, and energy use. The WEL is diverse enough to be used in other applications as well. A device called the WattNode ( must be added if you want to measure alternating current.