Enzo Oosthuizen, Property Development Manager at the Attacq Group, explains that the hotel’s certification was initiated in line with Attacq’s large sustainability footprint. Located within close walking distance of the Mall of Africa, public transport facilities and at least eight types of local amenities, The Nexus Waterfall site will also accommodate four office buildings, ranging in size from 4500 sqm to 7000 sqm.

Annelide Sherratt of Solid Green, sustainability consultant and Green Star AP on the project, says that the project has a safe, well-lit pedestrian walkway and a cyclist sidewalk that encourages building users to reduce carbon emissions through the use of non-motorised transport. Six parking bays for fuel-efficient and hybrid vehicles and six dedicated motorbike parking spaces have also been provided in the building’s basement.

Indoor Environmental Quality was a priority, and the design aims to optimise daylight and minimise potential health issues by specifying materials with a low VOC content, and ensuring that all selected gaseous and fire suppression systems and thermal insulants used for the development have an Ozone Depleting Potential (ODP) of zero.

To reduce the hotel’s operational energy consumption, an energy model of the building was generated in the design stages, which demonstrated a 48% improvement over a SANS 10400 notional building. A high level of thermal comfort is ensured by addressing the building’s internal operative temperatures through modelling; and sub-metering of major energy consuming systems was implemented to accurately monitor energy consumption and assess opportunities for energy savings. To reduce energy consumption associated with major appliances, two energy efficient appliances are provided within the scope of the main contract for each room – the TV and minibar fridge, both of which are Energy Star rated at level A.

Sub-metering of major water consuming systems is also in place, which enables automated leak detection to ensure that little to no water is wasted. Water efficient fittings were specified to ensure that occupant water usage is limited; and savings of approximately 30% are anticipated. Smart landscape irrigation measures have been implemented and it is expected that the installed water efficient irrigation systems will achieve a 70% reduction of potable water for irrigation.

A project specific Waste Management Plan has been developed to minimise the contribution of waste going to landfill. A dedicated waste recycling storage area is situated in the building’s basement to allow for storage of paper and cardboard; plastic, glass and cans; metals; and general waste. A monthly waste saving of 60% recycling and reuse is targeted.

Recommendations have also been made for the future choice of materials for expansions and refits. New construction should aim to reduce the quantity of Portland cement by 30% as an average across all concrete mixes; to ensure at least 60% recycled content of all steel by mass; and to ensure that at least 50% (by cost) of all timber products are specified to be Forest Stewardship Council (FSC) certified timber, reused or recycled timber.

And, in the interests of encouraging responsible resource consumption by building users and hotel guests, a Live Metering LCD display is intended to raise awareness on both current and historical resource consumption; and a Building Occupant Guide has been compiled to provide information that enables building management and users to optimise the building’s environmental performance.

As the first hotel to be Green Star certified in the Attacq portfolio, The Courtyard Hotel Waterfall City sets a new benchmark for the company’s future leisure developments.

The post Custom certification for The Courtyard Hotel Waterfall City appeared first on Solid Green Consulting.

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.

The post Residential Modelling: Case Study appeared first on Solid Green Consulting.