Energy Modeling for Historic Buildings

Modeling buildings built before the 2000s

Akshay Padwal avatar
Written by Akshay Padwal
Updated over a week ago

With heightened concern for the environment and rising fuel costs, many owners are looking for ways to reduce energy consumption in their historic properties. Additionally, in many locations, the updated energy codes are requiring owners to meet updated energy requirements to avoid fines. The following steps help to improve the energy efficiency of historic buildings by integrating building performance modeling in the process throughout the renovation process and picking the optimal upgrades for cost and energy.

//Step 1: Building Evaluation

The first step is to know how your building is performing in its current state. This can be done in a low-intensity way by looking at the utility bills and energy use showcased in them for heating, cooling, and water. Certain owners take the study deeper and utilize blower door pressurization tests to determine the airtightness of the buildings for a more accurate understanding of air infiltration rates. As the historic buildings get older, the energy performance of the building is affected due to various parameters. Therefore, the building evaluation is a crucial step when planning for the renovation of historic buildings.

//Step 2: Energy Modeling

At this step, you are representing the building
This can be done in two simple steps using cove.tool:
1. Select building type, add address and pick the 2007 energy code baseline

2. Bring the geometry in or model it manually

The geometry for historic buildings can be easily exported with the help of plugins (Revit, Rhino/Grasshopper, SketchUp) into cove.tool for the energy analysis.

Once the geometry is exported, next step is model calibration i.e. setting up the engineering inputs accurately to reflect the existing condition of the building. Often for historic buildings, air infiltration and thermal resistance values for the envelop are not well known and can significantly influence accuracy of energy modeling simulations as well as the actual energy performance of a building. If such values are not available, here are some assumptions and starting points for your historic buildings:

It's a great idea to start populating default inputs with ASHRAE 90.1 2007 prescriptive values if the building is built in 2000s since it is the oldest code version supported by cove.tool and it would provide a good ballpark value for the engineering inputs.

The mechanical systems need regular maintenance in order to perform efficiently as time passes by. It's a great idea to check when the last replacement/maintenance for mechanical system has been done so that the system parameters can be adjusted properly.

Furthermore, calibrate the model by manipulating the values of input parameters such as Lighting Power Density (LPD), Appliance Power Density, Occupant Density, Occupancy Schedule, etc. to reflect the current condition of the building.

The energy conservation strategies aim to reduce the consumption of energy by using energy more efficiently. The Energy Conservation Measures (ECM) for historic buildings may include strategies like envelope material upgrades, adding photovoltaic panels, adding sensors, upgrading lighting, implementing shading strategies, etc. and bundles are created by cove.tool's cost vs. optimization algorithm which consists of these strategies to help reach the targeted EUI for the building. Also, the bundles can be easily customized using the ‘Change Options’ tab within the Cove.tool web app. Furthermore, cove.tool uses an advanced algorithm to optimize for the first cost and assist in making rigorous metric-based decisions on cost and energy.

//Step 3: Monitoring the Updates

After the energy modeling and installation of the upgrades, the tests mentioned in step 1 can be utilized to monitor the energy efficiency for the historic buildings.

Here is a case study of a historic renovation project in cove.tool.

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