MENG 547 LECTURE 3 By Dr. O Phillips Agboola

C OMMERCIAL & INDUSTRIAL BUILDING ENERGY AUDIT Why do we audit Commercial/Industrial buildings Important for successful business performance Provide predictable positive cash flow Open doors to energy retrofit In the long run, reduce CO 2 emission Reduce over-head cost of a project, thereby increasing the feasibility of the project

Types of Commercial/Industrial buildings energy audits Walk-through Audit Utility Cost Analysis Audit Standard Energy Audit Detailed Energy Audit

Walk-through Audit This audit consists of a short on-site visit of the facility to identify areas where simple and inexpensive actions can provide immediate energy use and/or operating cost saving. Some Engineers refer to these types of actions as operating and maintenance (O&M) measured. Examples Replacing broken windows Insulating exposed hot water or steam pipe Adjusting fuel-air ratio Setting back heating set point temperature

Utility Cost Analysis Audit The main purpose of this type of audit is to carefully analyze the operating costs of the facility. Typically, the utility data over several years are evaluated to identify the pattern of energy use, peak demand, weather effects, and potential for energy savings. To perform this analysis, it is recommended that a walk-through survey is done first In performing this type of commercial energy audit the following are necessary Check the utility charges to rule out error in bills Determine the most dominant charges in the utility bills Peak demand charges and ways to shaves them Determine whether or not the facility can benefit from using other utility rate structure to purchase cheaper energy and reduce its operating costs. Determine if the facility is ripe for energy retrofit

Standard Energy Audit The standard audit provides a comprehensive energy analysis for the energy systems of the facility. In addition to the activities described for the walk-through audit and for the utility cost analysis described, the standard energy audit includes the development of a baseline for energy use of the facility and evaluation of the energy saving and the cost effectiveness of appropriate selected energy conservation measures. Typically, simplified tools are used in the standard energy audit to develop baseline energy models and predict the energy saving of energy conservation measures. Among these tools are degree-day methods, linear regression, simple payback analysis, net present value etc

Detailed Energy Audit It’s the most comprehensive form of energy audit and very time consuming. Specifically, the detailed energy audit includes the use of instruments to measure energy use for the whole buildings and/or for some energy systems within the building. For instance, lighting systems, office equipment, fans, chillers etc In addition, sophisticated computer simulation program are typically considered for detailed energy audit to evaluate and recommend energy retrofit for the facility

NOTE During auditing, hand held and clamp –on instruments can be used to determine the variation of some building parameters such as Indoor air temperature The luminance level Electrical energy use Also, the use of sensors are common e.g the use of Non-Intrusive Load Monitoring techniques (NILM)

General Procedure for a Detailed Energy Audit Step 1: Building and Utility Data Analysis This step evaluate the characteristics of the energy systems and the pattern of energy use for the building. The building characteristics can be collected from the architectural/mechanical/Electrical drawings The energy use pattern can be obtained from a compilation of utility bills over several years Analysis of the historical variation of the utility bills allows you to determine if there are any seasonal and weather effects on the building energy use

Practical steps Collect at least three years of utility date To identify a historical energy use pattern Identify the fuel types used Electricity, natural gas, oil etc Determine the fuel type that accounts for the largest energy use Determine the pattern of fuel use by fuel type Identify the peak demand for energy use by fuel type Understand utility rate structure (energy and demand rates) Peak demands and if cheaper fuel can be purchase Analyze the effect of weather on fuel consumption Perform utility energy use analysis by building type and size To compare against typical indices

Step 2: Walk-through Survey From this step, potential energy measures should be identified. The results of this step are important since they determine if the building warrants any further energy auditing work. Some of the tasks involved in this step are Identify the facility concerns and needs Check the current operating and maintenance procedures Determine the existing operating conditions of major energy equipment Lighting HVAC systems Motors etc Estimate the occupancy, equipment, and lighting Using energy density and hours of operation

Step 3: Baseline for Building Energy Use The main purpose of this step is to develop a base-case model that represents the existing energy use and operating condition for the building, This model is to be used as a reference to estimate the energy saving incurred from approximately selected energy conservation measures. The major tasks to be performed during this steps are: Obtain and review architectural, mechanical, electrical, and control drawings Inspect, test, and evaluate building equipment for efficiency, performance, and reliability Obtain all occupancy and operating schedules for equipment Develop a baseline model for the building use Calibrate the baseline model using the utility data and/or metered data

Step 4: Evaluation of Energy Saving Measured In this step, a list of cost effective energy conservation measures are determined using both energy savings and economic analysis. To achieve this goal, the following tasks are recommended Prepare a comprehensive list of energy Determine the energy savings due to the various energy conservation measures pertinent to the building using the balance energy use simulation model developed Estimate the initial costs required to implement the energy conservation measures Estimate the cost-effectiveness of each energy conservation measure using an economic analysis method

COMMON ENERGY CONSERVATION MEASURES 1. Building Envelops Walls, roofs, floors, windows and doors Insulations of these envelops Windows glazing, door fitting allowance Recommended energy conservations measures Additional Thermal Insulation This can be costly Replacement of Windows Reducing od Air Leakage

2. Electrical Systems Electrical energy cost constitute the dominant part of the utility bill Lighting Office equipment Motors - When luminance levels are above the levels recommended by the standard - Fastest growing part of electrical load e.g computers etc - The energy cost to produce electric motors can be a significant part of the operating budget of any commercial and industrial building

3. HVAC Systems The energy use due to HVAC systems can represent 40% of the total energy consumed by a typical commercial building Determine condition of the equipment Operating schedule Quality of maintenance Control procedures

Case Study/Assignment 1 Submission deadline: 19 th October 2012 A. Consider an apartment (2-3 bedroom apartment) and perform an energy audit. B. After the audit, perform a retrofitting evaluation of the apartment base on the energy audit of the apartment