This session evaluated whether it is more environmentally friendly to build new, highly efficient buildings or to re-use and convert older buildings. Case studies where presented comparing the life cycle assessment (LCA) of a new college administration building to Living Building Challenge standards and a factory complex converted to a museum for modern art. The discussion revealed that it depends greatly on the type of building and its future uses. For instance, it is always more worthwhile to convert old industrial buildings for other uses as demolishing them takes too much energy. Office and residences vary greatly depending on their location and construction.

Resources: The Greenest Building Study – by Quantis

Case Study: Rocky Mountain Institute – Lessons Learned

The Rocky Mountain Institute Innovation Center in Basalt, Colorado, holds LEED Platinum, International Living Futures Institute Zero Energy, PHIUS+ Source Net Zero, Architecture 2030 Challenge, and International Living Futures Institute Petal Certifications.

Rocky Mountain Institute Innovation Center

The building has been complete for a year and a check was carried out to determine how the building actually performed compared to the modelled predicted performance. It was found that the building out-performed the model in some cases and did not in others. The main issue was that the model did not take the low infiltration rates into account in winter conditions and overestimated the usage of the heating system. This discovery led to an update of the design software so that the model now more closely replicates the actual performance of the building; and the more accurate software can now be used on future buildings.

Another challenge was getting the staff used to the new more open office layout. Fortunately, this had been considered in the design and many quite refuge spaces are located around the building, which also allow for flexibility in the working environment from a thermal, acoustic and physical comfort point of view.

The Innovation Center is the highest-performing building in the coldest climate zone in the U.S., producing more clean energy than it uses on an annual basis plus enough to power six electric vehicles. It is one of only 200 net-zero commercial buildings in the U.S. as of 2016, and provides a leading example of buildings that can solve the climate crisis. The building achieved this through a heavily integrated design process with the whole professional team, contractor and client; clever passive design; and on-site PV generation.

Building Tour Green Day Out – Living Building Challenge

Of particular interest to the Solid Green team was a visit to three buildings designed to meet the Living Building Challenge. The Kern Centre, a 2-storey 1500sqm College building, generates 105% of its energy on site and reduces water consumption by 95%. The building is a beautiful space and displays all green initiatives on a touch screen at the central entrance, including live metering of the water and energy consumption. The building has composting toilets and uses a composting system for its sewer. Rainwater is harvested, cleaned and reused.

The Kern Centre

Another Highlight was the Hitchcock Centre for the Environment. This small 850sqm building functions as an environmental education centre. It is registered under the Living Building Challenge but has not been in operation for 12 months yet. Features include a beautiful wooden structure, exposed services and transparent rainwater tanks so children can see the rainwater tank filling up during a storm. The building also has a composting toilet and a composting system in the basement.

Hitchcock Centre for the Environment

As Solid Green is embarking on two Living Building Challenge projects in Cape Town, this was a particularly inspiring day – from chatting to the consultants working on these projects to knowing that it is possible to create a regenerative building! If you would like to know more about the Living Building Challenge, please contact Marloes Reinink at marloes@solidgreen.co.za. As an ambassador for the Living Building Challenge in South Africa, Marloes can present an “Introduction to the Living Building Challenge” at your offices.

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Chilufya Lombe, Director at Solid Green, says:

One of the most important aspects of passive design is fully understanding the local climate and making sure that the building is able to take advantage of the prevailing conditions. Solid Green has an extensive library of detailed weather data that are used to conduct simulations and analyse weather data.

1. Sunlight and Thermal Modelling

The area is characterised by high diurnal temperature swings for large percentages of the year. This large difference between maximum and minimum daily temperatures indicates that there is a lot of potential for using thermal mass for passive cooling. Low night time temperatures means the building fabric can store ‘coolth’ and release it during the day, greatly reducing the need for active cooling. Fig. 1.1 – 1.5 below illustrate the modelling for this building in these specific climatic conditions.

Sun Path Diagrams

Fig. 1.1 – 1.2 represents the path the sun follows with respect to the site location. This is often the easiest way to help design teams visualise the impact of the sun on the building. All shading elements as indicated on the tender drawings are captured in the actual building model; and self-shading from the building’s own form is also accounted for in the model. No adjacent buildings are present on site that can have overshadowing impact.

Sun Path Diagram, Fig. 1.1

Sun Path Diagram, Fig. 1.2

Temperature Distribution Charts

Fig. 1.3 – 1.5 show the temperature and humidity distribution for different months of the year. Every hour of the year is represented.

Temperature Distribution, Fig. 1.3

The percentage of hours above 26 °C is a good indicator of how much discomfort should be expected when using natural ventilation for cooling.

Temperature Distribution (Day), Fig. 1.4

With the correct treatment of the façade, night time temperatures should always be comfortable in this climate. It is also clear that winter temperatures can fall quite low and heating will be required in winter months.

Temperature Distribution (Night), Fig. 1.5

2. Passive Design Modelling

A baseline model was created using known design parameters and best-practice inputs for different building elements. This baseline was then used to test the impact of various passive design elements.

To truly optimise a building, a large number of combinations must be tested to ensure the interconnectivity between important design variables is fully assessed. Take glazing as an example: if the glazing specification is changed, then shading requirements, heating and cooling loads, thermal mass and natural ventilation requirements will also change. Fig. 2.1 illustrates how, with just a few options for various building elements, you can generate a large number of combinations to test.

Parametric Design Combinations

The most efficient set of solutions must be identified and assessed for accurate recommendations to be made. This is one of the big advantages of optimisation – you typically end up with a number of optimal solutions and have the choice to decide which solution best meets the design objectives.

Parametric Design Combinations, Fig. 2.1

3. Building Fabric Investigated

Thermal properties of standard materials were used directly from the extensive DesignBuilder materials database. The following tables represent various changes that can be implemented to achieve both the most energy efficient and thermally comfortable solution.

Glazing – options investigated, Fig. 3.1

Roof Insulation – options investigated, Fig. 3.2

External Walls – options investigated, Fig. 3.3

Ground Floor – options investigated, Fig. 3.4

4. Summary of Results

Based on the results generated from the above, recommendations were then made with regards to the best combination of building fabric. The initial design was over-insulated for this climate and led to the building not being able to cool down passively at night. The table below shows that the proposed changes not only reduce the buildings energy use for active cooling but also save the client money.

Best combination of building inputs:

Best Combination, Fig. 4.1

Fig. 4.2 shows the savings by means of the most effective combination of factors.

Overall Savings, Fig. 4.2

5. Conclusion

The baseline building can be improved by 30% overall in HVAC energy by optimising the building fabric. That represents 30% less energy to offset if the client would like to make the house carbon neutral. Reducing the cooling load effectively decreases the number of hours that the building will require active cooling. Although the overall heating has been increased, the energy consumption over a whole year has been decreased because heating is only required for two and a half months. These recommendations are therefore in line with the client’s objectives for an energy and cost efficient home.

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